Syrian anti-Assad fighters have shot down a government warplane south of Aleppo and captured its pilot on Tuesday, a monitoring group said.

The incident occurred as fighting renewed across swaths of the country threatening to upend a fragile truce.

Syria’s military confirmed that a plane on a reconnaissance mission had been shot down and said it was hit by a surface-to-air missile. The pilot had bailed out and efforts were in progress to rescue him, it said.

The Syrian Observatory for Human Rights said fighters from al Qaeda’s Nusra Front group captured the pilot and took him to one of their headquarters in the area. There was no immediate rebel comment on the use of an anti-aircraft missile.

AFP cited a source saying it was “likely that Al-Nusra Front shot down the plane and took the pilot,” adding that the plane had been hit by heavy machinegun fire.

However, sources close to the Free Syrian Army told Asharq Al-Awsat that they were the ones who downed the fighter jet.

The Observatory said a plume of smoke was seen as the plane caught fire before it fell in the Talat al-Iss highland, where al Qaeda-affiliated rebels have come under heavy bombardment by Syrian and Russian planes since they captured the area this week.

Videos on social media also showed footage of an aircraft and pictures of the wreckage of a burnt plane surrounded by militants.

In video footage circulated on social media purporting to show the scene where the plane came down, a dozen men crowd around a man lying in the dirt.

Some of them cry: “He’s Syrian, he’s Syrian!” and others yell: “Get his weapons off him!”

The authenticity of the footage has not been confirmed.

Aerial supremacy has been a major advantage for the Syrian army that has been battling insurgents seeking to overthrow President Bashar al-Assad.

Fighters opposing Assad’s regime have long demanded anti-aircraft weapons to offset the impact of devastating aerial raids by Syrian forces and, since September, also by Russian planes.

Last month, Syrian opposition denied a Russian Defense Ministry report that an anti-aircraft missile had been used to shoot down a Syrian warplane in Hama province.

Reuters contacted officials in three opposition groups who reiterated previous statements that that plane had been shot down with anti-aircraft guns.

A fragile “cessation of hostilities” truce has held in Syria for over a month as the various parties try to negotiate an end to the five-year-old civil war.

But the truce excludes ISIS and Nusra Front, and air and land attacks by Syrian and allied forces continue in parts of Syria where the government says the groups are present.