Syrian activists say at least four children have been killed when government shelling hit their school in a rebel-held town outside the capital Damascus.

The Ghouta Media Center and the Syrian Observatory for Human Rights say a shell landed Tuesday at the gate of a school in Jisreen, a town in the Eastern Ghouta suburbs of Damascus. The shelling killed five, including four children, and left many injured.

Residents of the Eastern Ghouta suburbs have been living under a suffocating government blockade amid intense bombings. The violence and siege have continued even though the suburbs are part of a de-escalation agreement guaranteed by Syrian government backers Russia and Iran.

On Monday, the United Nations said it reached thousands of the suburbs residents for the first time in over a month.