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 (280 km) 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.
Miller told reporters that at least two victims were transported to a hospital but she was unaware of their condition. The subsequent police statement, posted online, said, authorities "have confirmed there were multiple victims," with at least two taken to hospital, adding, "Children are among the victims."
Silver Rail Elementary School serves grades kindergarten through fifth grade, roughly ages 5 to 11. It has about 450 students and 40 staff members, Miller said.