Airstrike on rebel-held Syrian city inflicts casualties

This photo provided by the Syrian Civil Defense group known as the White Helmets, shows Civil Defense workers and Syrian citizens inspecting damaged buildings after airstrikes hit Maarat al-Nuaman town, in Idlib province, Syria, Saturday, March 25, 2017. (Syrian Civil Defense White Helmets via AP) (The Associated Press)

In this photo provided by the Syrian Civil Defense group known as the White Helmets, Civil Defense workers help their teammate after airstrikes hit a main street, killing many people, activists said, in the Damascus suburb of Hamouriyeh, Syria, Saturday, March 25, 2017. The airstrikes, of which some activists said included Russian air raids, concentrated on the rebel-held northwestern province of Idlib, the central province of Hama and suburbs of the capital Damascus that has come under attack by insurgent groups over the past week. (Syrian Civil Defense White Helmets via AP) (The Associated Press)

This photo provided by the Syrian Civil Defense group known as the White Helmets, shows Civil Defense workers putting out a fire in a house following airstrikes hit Maarat al-Nuaman town, in Idlib province, Syria, Saturday, March 25, 2017. (Syrian Civil Defense White Helmets via AP) (The Associated Press)

Syrian opposition activists say airstrikes have struck the northwestern rebel-held city of Idlib, inflicting casualties.

The Britain-based Syrian Observatory for Human Rights says the Friday night attack struck a prison run by militants, killing at least 16 people including prisoners and prison employees. It added that women were among the dead as well.

The group, which has a network of activists around the country, said some people were killed by gunfire as prison guards chased some detainees who tried to flee after the attack.

The Local Coordination Committees, another opposition activist group, said five air raids struck the city without giving further details.

Idlib is a stronghold of Syrian insurgent groups and is regularly targeted by Syrian and Russian warplanes.