METHUEN, Mass. -- An 11-year-old child was killed Monday and his 8-year-old brother critically injured in an accident at the Tenney School on Pleasant Street in Methuen.

A large gate from an iron fence fell on four children as they were riding their bicycles on the school grounds, police said.

The dead child was identified as Timothy Dileo. His brother, Andrew, was taken to Children's Hospital in Boston. A third brother, 13-year-old Steven, was slightly injured.

A fourth child, Brandon Leport, 13, was unhurt.

Police said the accident, which took place about 3:30 p.m., is under investigation. The school was closed for the Labor Day holiday.

All four were students at the school.

"Our thoughts and prayers are with the family," Methuen Mayor William Manzi said.

The school will open for the school year as scheduled on Wednesday. Officials said counselors would be made available.