PORTLAND – Two pedestrians suffered head injuries when they were hit by an off-duty police officer driving home from work, authorities said.

Officer Jay Twomey’s truck collided with Kathleen Racki and Glen Loper when the two stepped from between two parked cars into the street on Tuesday, according to Portland police.

Twomey immediately called 911 from his mobile phone and voluntarily gave blood for testing, said Chief Michael Chitwood. Results from the tests were not immediately available, but Chitwood said there was no indication that speed, reckless driving or alcohol was a factor in the crash.

Loper, 27, of Falmouth, was listed in critical condition Wednesday at Maine Medical Center, while Racki, 27, of Portland, was in serious condition. Both suffered head trauma and other injuries, according to Chitwood.

Several witnesses told police that Twomey was driving west on Park Avenue near Deering Oaks Park when Racki and Loper stepped into the street without looking, Chitwood said.

Twomey is not being placed on leave, he added. “We’re handling it as an accident,” Chitwood said. “He just happens to be an off-duty police officer.”