(CNN) A Russian warplane was shot down Saturday in Syria, according to Russian state-run news agencies.

The Russian Ministry of Defense confirmed one of its Su-25 warplanes was downed in Idlib province in northwest Syria, state media outlet RIA Novosti reported.

Militants shot down the plane in an area controlled by al-Nusra Front fighters, according to the RIA Novosti report. Russia and Turkey, which is responsible for a de-escalation zone in Idlib, were taking measures to return the pilot's body, the defense ministry said.

The ministry said more than 30 militants in the area were killed in a retaliatory strike, according to RIA Novosti, citing "radio intercepts."

The defense ministry said the pilot was able to eject from the aircraft before it crashed, according to state-run news agency TASS, but died while fighting al-Nusra fighters.

TASS reported that "according to preliminary information, the plane was shot down from a portable anti-aircraft missile system."

But a witness who spoke to CNN via Skype on condition of anonymity said the jet was shot down by Free Syrian Army fighters with a group called Jaish al-Naser as two jets were "striking the village of Massaran on the southern side of Saraqib."

The witness said that a pilot parachuted. A Free Syrian Army fighter in the area told the source that the pilot "engaged with FSA fighters with a pistol but they killed him eventually."

The source left the area after the second jet fired more missiles.

Other witnesses said the pilot was taken from the crash site, according to Rami Abdel Rahman, director of the Syrian Observatory for Human Rights, a UK-based monitoring group. It was unclear whether the pilot was alive or dead, he said

The Idlib Media Center, an anti-government activist group, posted images that purportedly show the plane's wreckage.

Smoke billows from the site of the downed Russian plane Saturday in the northwest province of Idlib.

Syrian President Bashar al-Assad's regime recently resumed airstrikes on rebel-held areas such as Idlib province, prompting tens of thousands of civilians to flee their homes, according to UN officials.

Idlib has long been the region where civilians and fighters have gone as they fled rebel-friendly areas under siege by the Syrian regime.

With the help of Russian forces, the Syrian government has managed to take back much of the country held by rebels. The regime has launched an offensive to retake Idlib, the only province that has come under full rebel control in the nearly 7-year-old conflict.