At least 27 people were killed and dozens injured when a Syrian army fighter jet crashed into a busy marketplace in the rebel-held northwestern town of Ariha on Monday, August 3, residents and witnesses said.

Most of the dead were civilians on the ground in the Idlib provincial town that fell to a coalition of Islamist insurgents in May, according to the Britain-based Observatory for Human Rights, which tracks violence across Syria.

Scores were also injured, according to the monitor and witnesses. There was no immediate reaction from the Syrian army.

“The plane had dropped a bomb on the main Bazaar street at low altitude only seconds before it crashed,” said Ghazal Abdullah, a resident who was close to the incident.

The Observatory said the jet was not shot down.

Fighting has intensified of late in rural Idlib province between government forces and an insurgent grouping called Jaish al Fateh, or Army of Conquest, which includes Syria’s al Qaeda offshoot Nusra Front.

Ariha’s fall had left the insurgents in control of most of Idlib province, which borders Turkey and neighbors Latakia, the heartland of President Bashar al-Assad’s Alawite sect, on the Mediterranean coast.

Most of the rich agricultural region, however, has since come under heavy aerial bombardment by Assad’s forces in a counter-offensive to regain lost ground.

The army has fought back using heavy air strikes to beat back insurgent advances into the mountains of Latakia province that brought them closer to government-held coastal areas north of the capital Damascus.

Syria’s western flank, fringing both the Mediterranean coast and the Lebanese border, contains Syria’s major cities including Damascus and is seen as crucial for Assad’s hold on power.