Public schools in Trumbull were closed Monday due to extreme cold after transportation issues made it unsafe to run buses.

The school superintendent said a large number of buses failed and could not operate safely.

All after-school activities were also canceled.

The decision was made close to the start of the school day.

“I am very sorry to share this news so close to the start of the school day,” Superintendent of Schools Martin J. Semmel said in a statement.

He said officials did everything possible to avoid a closure and made the decision only when it became clear transportation could not run safely.

The closure will count as an emergency school closure day, and information on a makeup day will be shared soon, Semmel said.