Two of the soldiers who were killed during a lunchtime attack Tuesday in Mosul, Iraq, are from the Maine National Guard’s 133rd Engineer Battalion, officials confirmed. The 500-person battalion left the state last December and is the largest group of Maine troops deployed to combat since World War II.

At least 20 people are dead after the explosive attack on the soft-roofed dining hall at the U.S. military base in Iraq and another 60-plus are injured, with approximately 10 of the wounded reportedly being members of the 133rd, one of two Maine National Guard units in Iraq. The 133rd has units based in Portland, Gardiner, Skowhegan, Belfast, Lewiston, Norway and Saco.

Battalion officials said names of the casualties were being withheld pending notification of next of kin. Military officials said later in the day that 19 of the dead were U.S. soldiers.

Gov. John Baldacci was notified of the attack, which occurred at about 4 a.m. EST, by Brig. Gen. John Libby, adjutant general of the Maine National Guard. Baldacci confirmed that two Maine soldiers were killed and 10 wounded.

Bill Nemitz, a Portland Press Herald columnist, and Press Herald photographer Gregory Rec are embedded with the 133rd and reported that there were two Maine soldiers dead and 12 wounded. Their story was posted just before 3 p.m. Tuesday on the newspaper’s Web site, MaineToday.com. Nemitz identified one of the wounded as Sgt. Christopher Rushlau of Portland.

Nemitz said it was a powerful explosion that ripped through the crowded dining facility at Forward Operating Base Marez. The attack was one of the bloodiest attacks of the war against U.S. forces.

Eyewitnesses emerging from the dining hall said the blast struck in the center of the open seating area where an estimated 400 American and Iraqi soldiers and civilian contractors were eating at the time, Nemitz reported.

Sgt. Mark Haas of Brunswick was filling his plate at the salad bar when the blast went off by a cluster of coffee urns about 50 feet away.

“I saw the roof give way, then I saw the fireballs,” said Haas, who was not injured. “It knocked me right off my feet.”

Haas tried to get to the area where members of the 133rd were seated but was swept out with a rush of soldiers evacuating the area. He went back to the 133rd’s encampment and called out for help from his fellow Maine soldiers.

Up and down the 133rd’s barracks, soldiers grabbed their tactical vests and helmets and sprinted toward the dining facility, where a thick plume of white smoke rose through a gaping hole in the roof, Nemitz said.

Outside the dining hall, soldiers from the 133rd and other units carried the wounded by hand and on litters and tables to a triage area located outside the dining hall entrance.

Brig. Gen. Carter F. Ham, commander of Task Force Olympia, said during an interview Tuesday evening with Nemitz that the cause of the explosion is under investigation by both the U.S. military and the FBI to determine whether it resulted from “indirect fire,” a rocket or mortar round fired into the cavernous, canvas-covered facility, or if some type of device was placed and detonated inside the building.

The camp is located about 20 miles from Mosul, which is in northern Iraq and is the country’s third largest city. Pentagon officials said there are about 8,500 U.S. troops in the Mosul area, which is 220 miles north of Baghdad.

Maj. Peter Rogers, director of public affairs for the Maine National Guard, said he had received numerous calls from family members inquiring about their loved ones who are stationed in Mosul.

Linda Zadakis of Mexico said she had not heard from her daughter, Sgt. Melissa Zadakis, but got a call from the wife of a serviceman in the 133rd who said her daughter was not among those who were injured.

Zadakis said it was difficult waiting to hear who the casualties were since the members of the unit are so tight-knit.

“It rips your heart out because not knowing who is grieving is very hard,” she told The Associated Press.

She said her daughter, who is 20, is part of the battalion’s life-saving unit and is trained in emergency care. “I’m sure she’s busy with all the injured,” she said.

Mark Wright of Biddeford e-mailed the NEWS Tuesday evening to say his brother, Sgt. Scott Wright, is safe and uninjured. Sue and Richard Dorsey of Centerville also contacted the NEWS to say their son, Sgt. James T. Dorsey, and his girlfriend, Spc. Valeri J. Collins, are safe. Brian Spaulding of Knoxville, Tenn., e-mailed the NEWS to say his brother, Sgt. William H. Spaulding of Brooks, is safe.

Other Maine residents, who keep daily tabs on their loved ones in Iraq by e-mail, were awaiting word.

Baldacci offered comfort to families of the 133rd.

“We will provide support to the families. This is a very difficult time, especially during this holiday season. As before, Maine people pull together. This tragedy weighs heavily on us all,” the governor said.

U.S. Sens. Olympia Snowe and Susan Collins of Maine offered condolences to the families of those killed from the 133rd.

“My thoughts and prayers are with the families and loved ones of the two brave Maine soldiers who died today fighting for their country in Iraq,” Snowe said. “We will forever remember the extraordinary sacrifice and courage they exhibited.”

Collins said, “My thoughts and prayers are with the victims and their families.”

In prepared statements, U.S. Reps. Tom Allen and Michael Michaud of Maine said they were heavy-hearted after hearing about the attack at the base, which is used jointly by the United States and Iraq.

“Today, the people of Maine are shocked and saddened by the report that members of the Maine-based 133rd Engineer Battalion were among the casualties in the deadly noontime attack,” Allen said.

“Maine has once again been struck by tragedy,” Michaud said. “We can only imagine how hard this must be for the family members of the 133rd and all our military families. Words are of little consolation, but we as a nation are forever indebted for their sacrifice.”

Soldiers in the engineering battalion build, maintain and repair bridges, command posts, airfields and work on other construction projects. The battalion is due to return to Maine next spring.

Allen noted that “this is not the first time [the 133rd] has suffered casualties during the Iraq war. Last April, Spc. Christopher Gelineau of Portland was killed and three of his comrades from the 133rd were wounded during an insurgent attack on their convoy.”

Soldiers from the 133rd have been injured during other incidents as well.

Mosul became an increasingly troubled spot for soldiers in Iraq in November when U.S. and Iraqi troops invaded the insurgent stronghold of Fallujah, west of Baghdad. On Sunday, two roadside bombs and a car bomb targeted U.S. forces in Mosul.

A radical Muslim group, the Ansar al-Sunnah Army, claimed responsibility for Tuesday’s blast, which, in addition to U.S. military personnel, killed U.S. contractors, foreign national contractors and members of the Iraqi army, Ham said.

Officials could not break down the toll of dead or wounded among the groups.

The dead included two soldiers from the Richmond, Va.-based 276th Engineer Battalion, according to Jeremy Redmon, a reporter for the Richmond Times-Dispatch embedded with the troops in Mosul.