A Russian military transport helicopter was shot down on Monday in the Syrian province of Idlib, killing the three crew members and two officers on board in the deadliest episode for the Russian military since it intervened in the country, Russian officials said.

The Mi-8 helicopter was brought down by ground fire as it returned to the Khmeimim Air Base from a mission to the embattled city of Aleppo, according to the Russian Defense Ministry.

Video, which was posted on Facebook by antigovernment activists shortly before the Russian Defense Ministry confirmed the attack, showed two burned bodies on the sand about 300 feet from what appeared to be a helicopter in flames.

In the video, a number of men, some of them armed, cheered around the bodies, shouting “Allahu akbar.” One of them jumped on a body, joyfully.

A set of images, also released online, showed two Russian drivers’ licenses — one belonging to a young woman, another to a young man — and a laminated Orthodox icon of God. It was not possible to establish the names of the people pictured on the licenses.

Dmitri S. Peskov, a spokesman for the Russian president, Vladimir V. Putin, confirmed that all those on board had been killed, according to the news agency Tass, and he expressed condolences to the victims’ families.

The Syrian Observatory for Human Rights, which opposes the Syrian government and tracks the conflict from Britain through contacts in Syria, said the helicopter crashed near the village of Saraqib in Idlib Province.

The aircraft had recently delivered aid to two Shiite villages nearby that have long been surrounded by Sunni rebels, the group said.
None of Syria’s many rebel groups immediately claimed responsibility for shooting down the helicopter. But at a press briefing on Monday, Lt. Gen. Sergei F. Rudskoi, a senior member of the Russian general staff, said it was downed over territory controlled by the Nusra Front and “the so-called moderate opposition.”

Last week, Russia established several humanitarian passages in Aleppo to let civilians and insurgents leave the area. So far, 324 civilians and 82 militants have left the city through them, said General Rudskoi.

Citing the need to fight terrorists in faraway territories before they arrived in Russia, Mr. Putin began a military operation in Syria at the end of September in support of the government of President Bashar al-Assad.

He ordered a partial withdrawal of Russian forces from Syria in March, but military operations continued, although at a lower intensity.

A number of similar episodes have occurred over the course of Russia’s involvement in the Syrian war.

Militants belonging to the Islamic State shot down a Syrian Mi-25 helicopter in July, killing two Russian crew members on board.

A Russian fighter jet was shot down by Turkey in November, with the captain killed by insurgents’ ground fire as he descended to earth after ejecting from the plane. Another helicopter was shot down during the rescue mission, killing a crew member.

That episode provoked a standoff between Russia and Turkey, which ended with President Recep Tayyip Erdogan apologizing to Mr. Putin in July.

After the downing of the Mi-25 in July, Russia sent Tu-22M3 bombers to hit Islamic State targets in the Syrian areas of Palmyra, Es-Suhne and Arak.

Russia also launched retaliatory strikes after the Islamic State’s affiliate in Egypt claimed to have brought down an Airbus A321 passenger airliner over the Sinai Peninsula, killing all 224 people on board.