Kerry Lujan (19) was killed by two vehicles in a double hit-and-run accident.

A 34-year-old Windsor man has been arrested in the fatal hit-and-run of a woman walking across U.S. 287 early this morning.

Jeremy Raisch was identified as the driver of a black 1999 Nissan Pathfinder that was traveling northbound on 287 near Longmont about 1:22 a.m. when it struck Cerridwyn Ursula-Laujan, 19, of Boulder, according to the State Patrol.

Investigators are seeking the public''s help in identifying the driver of a second vehicle that ran over the woman.

A good Samaritan stopped and tried to help Ursula-Lujan, said Cpl. Jeremy Miller of the State Patrol.

"He apparently saw her lying in the roadway, turned around to help her, at which point she was hit by another vehicle," Miller said.

Ursula-Lujan was airlifted to Denver Health Medical Center where she was pronounced dead.