Lt. Abel Tenorio said this morning a Vallejo man had seen the teen starting the first fire with a lighter and yelled at him.
The boy ran but then allegedly started two more small fires, Tenorio said. Police located the boy and the witness identified him as the arsonist. He was booked into juvenile hall Thursday.
The fires burned about 3 acres along the tracks in the area of Illinois and Sacramento streets. The first fire was reported around 2:30 p.m.
Eighteen firefighters responded and contained the fires by 4:30 p.m., Vallejo Fire Department Capt. Patrick Dunn said.
There were no injuries and no structures burned.