WINTHROP — No one was injured this morning when smoke on a school bus forced the evacuation of about a dozen children on Narrows Pond Road.

The children were transferred to another bus and a second bus finished pick up the children along the remainder of the route, according to Winthrop Fire Chief Dan Brooks.

“I think some oil spilled on the engine and just smoked a little bit,” Brooks said.

Brooks said the smoke was minor and presented no risk, but the children were taken off the bus about 7:50 a.m. as a precaution. On that school bus, the engine sits under the bus, he said.

The bus was driven back to the station. Brooks said the firefighters were on the scene for about 30 minutes.

The Winthrop school buses are operated by Northeast Charter School Bus Services Inc., Winthrop School Bus Division.

Brooks said the Northeast transportation manager Christy McLain responded to the scene and assisted with the transfer of students.

Sandy Flynn, administrative assistant to the Winthrop schools superintendent, called the parents of every child on the bus and all were checked and cleared by the school nurse, she said.

“The kids were amazing,” Flynn said. “Apparently they evacuated just as they were supposed to. They all got to school and have great stories to tell.”