A person with a gun opened fire on Thursday at an elementary school in Bend, Oregon, wounding multiple victims, including children, before the assailant was killed, possibly by an armed onlooker, according to police.

CNN and CBS News, citing law enforcement sources, reported that one adult and three children were killed in the violence, but it was not immediately clear whether the shooter was included in that death toll.

Police in Bend, a city of about 100,000 residents in central Oregon, 175 miles southeast of Portland, said the first call they received from the 1 p.m. incident “indicated that an unknown man had shot into a car” at Silver Rail Elementary.

Police officers arriving seconds later found that the suspect had been shot dead, possibly by a bystander, police said in a statement.

Sheila Miller, a spokesperson for the Bend Police Department, told reporters investigators had yet to confirm who shot the suspect.