Authorities believe at least five people are dead following a shooting at an elementary school in Bend, Oregon.
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.
CBS News later reported the shooter was 16 years old.
Both officials said the death toll was preliminary and could change.
Sheila Miller, communications manager for the Bend Police Department, told reporters she had no information about the shooter, who was shot and killed.
A 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".
Ms Miller told reporters investigators had yet to confirm who shot the suspect.
First responders at the scene following a shooting at Silver Rail Elementary School in Bend, Oregon. (Reuters: Rob Kerr)
"We don't have confirmation yet of who shot the suspect; it may have been a bystander," Ms Miller said.
Authorities received a call about a shot fired into a car outside Silver Rail Elementary about 12:59pm, local time, and arrived on scene within minutes.
She said further 911 calls came from inside the school.
Police arrived on campus within minutes, and the shooter was shot almost immediately, Ms Miller said.
The attacker was shot and went down inside the school soon after police arrived, Ms Miller said.
Silver Rail Elementary said it was under lockdown, the Bend-La Pine school district wrote on Facebook.
"We're in the process at this time of going room by room and evacuating each of the people who are in that school," Ms Miller said.
"This is the kind of thing we never want to see happen in Bend. It's devastating," she said, pausing to control her emotions.
Bend is a city of some 100,000 people in central Oregon, about 280 kilometres south-east of Portland.
Silver Rail Elementary School serves students from kindergarten through fifth grade, roughly ages 5 to 11.
It has about 450 students and 40 staff members, Ms Miller said.
Reuters/AP