ORONO — The call came in at 9:29 a.m. Friday to Regina Kocur, dispatcher at the Orono Fire Department. Chlorine leak at the treatment plant. Two people still in the building. The report was fake, the start of a disaster exercise, but Lorin LeCleire, incident commander, and other crew members were quick to head out the door.

Fire engines and ambulance crews from Orono and police cars from Orono and Old Town converged near the treatment plant. A few residents of Broadway, the street the sewage treatment plant is on, stuck their heads out of doors. They were curious, a bit irritated, that the town had failed to notify them of a disaster drill, they said.

The lack of notification was one of few glitches in an exercise that went smoothly, according to all involved. The drill climaxed a weeklong course in hazardous materials training. The course prepared Orono Fire Department employees to deal with chemical leaks and other technical disasters.

Being a firefighter means more than aiming a hose at a burning building these days. It often demands skills at the technician level, said Joe Burgess, course instructor. Federal law now requires fire departments to be skilled in rescue techniques to the level of complexity needed in all disasters to which they might have to respond, Burgess said.

At the scene, LeCleire quickly organized the workers into teams. Sites were designated as the “hot area,” the treatment plant; the warm area where men would be hosed off to prevent contamination; and the cold area, which was the safety zone.

Some men zipped themselves into hooded white outfits that looked like spacesuits. These few would enter the building from which a cloud of steam — supposedly chlorine — escaped.

Inside the suits, the men breathed a mixture of air and oxygen and talked with commanders by portable radio. A team of three men, backed by another team of suited men, walked slowly toward the treatment plant, like the first walkers on the moon.

Others set up a “Dcon” center — decontamination center — about 100 yards from the plant. The Dcon center was the first stop for people who had been inside the treatment plant. There they were hosed down, then taken to a shower and scrubbed again to get rid contamination that likely would be sticking to their clothes. A third, curtained-off area would be used to remove the victims’ clothing. It was not used Friday. An ambulance crew waited to treat the supposed victims. The police reportedly went door to door to evacuate streets downwind of the plant.

Inside the treatment plant, the situation was grim. One of the firefighters had fallen so rescuers had to deal with him in addition to the two downed employees inside. One goggled treatment-plant employee ran from the building and collapsed on the ground. The spacesuit-clad crews ignored him; a key rule in the training is to get to the “hot” zone inside the building as quickly as possible. They alerted medical crews over the radio of the downed employee.

The “rescues” were made, and employees and firefighters proceeded to the Dcon center, then to a waiting ambulance where crews took vital signs.

The plan called for two of the three workers to be severely injured and taken to the hospital. One would be released. In reality, all three simply walked off after treatment.

Breathing chlorine causes pulmonary problems and respiratory arrest, and death in severe cases.

The simulation gave the firefighters confidence in their ability to handle a potential chemical leak, said Mike Sturgeon, a communications officer at the scene.

Nancy Orr, town manager, watched the simulation. Orr has been an advocate for the training which, she said, is provided at no cost to taxpayers. Robert Burke, Orono fire chief, helped coordinate public information on the event. The program and equipment costs, around $30,000, will be funded through the University of Maine, the Orono water pollution control plant and the Orono water district.