Rescue workers have found fragments of a Russian jet that plunged into the Black Sea on Christmas, the country’s emergency ministry announced Monday, as a top transportation official said pilot error or a technical fault is likely to be the cause of the crash.

The ministry said in a statement Monday that divers this afternoon found several fragments of the plane one mile away from the shore and 82 feet under the sea. It said some of the debris has been recovered, and the divers are going back into the water to search for more. By Sunday evening about 11 bodies were recovered and fragments of bodies were also found.

All 84 passengers and eight crew members on the Russian military’s Tu-154 plane are believed to have died when it crashed two minutes after taking off at 5:25 a.m. in good weather from Sochi. The passengers included dozens of singers in Russia’s world-famous military choir.

Transport Minister Maxim Sokolov said in televised remarks that investigators are looking into a possible pilot error or a technical fault and that a terrorist attack was not among the main theories.

Sokolov officially ruled out terrorism after saying Sunday that investigators were looking into every possibility for the crash. Several experts noted factors that suggested a terror attack, such as the crew’s failure to report any malfunction and the fact that plane debris was scattered over a wide area.

The plane was taking the Defense Ministry’s choir, the Alexandrov Ensemble, to perform at a New Year’s concert at Hemeimeem air base in Syria’s coastal province of Latakia. Those on board also included nine Russian journalists and a Russian doctor famous for her work in war zones.

Russian President Vladimir Putin went on television to declare Monday a nationwide day of mourning.

“We will conduct a thorough investigation into the reasons and will do everything to support the victims’ families,” Putin said.

CHOIR TRAGEDY: A LOOK AT RUSSIAN ENSEMBLE WIPED OUT BY CRASH

The Black Sea search area — which covered over about 4 square miles — was made more difficult by underwater currents that carried debris and body fragments into the open sea. Sokolov said the plane’s flight recorders did not have radio beacons, so locating them on the seabed was going to be challenging.

The Tu-154 is a Soviet-built three-engine airliner designed in the late 1960s. More than 1,000 have been built, and they have been used extensively in Russia and worldwide. The plane that crashed Sunday was built in 1983, and underwent factory check-ups and maintenance in 2014 and this year, according to the Defense Ministry.

Magomed Tolboyev, a decorated Russian test pilot, said it was clear that all on board had died in the crash.

“There is no chance to survive in such situation,” he said, according to the Interfax news agency.

Before Sokolov spoke to reporters in Sochi, senior Russian lawmakers had ruled out a terror attack, arguing that the military plane was under reliable protection. Security is particularly tight in Sochi, the Black Sea city that hosted the 2014 Winter Games and is regularly visited by Putin, who often receives foreign leaders at his residence there.

But some experts said the crew’s failure to report a malfunction pointed at a possible terror attack.

“Possible malfunctions … certainly wouldn’t have prevented the crew from reporting them,” Vitaly Andreyev, a former senior Russian air traffic controller, told RIA Novosti.

Alexander Gusak, a former chief of a SWAT team at the main domestic security agency, the FSB, told Dozhd TV that Russian airports are still vulnerable to terror threats despite security cordons.

“It’s possible to penetrate them. It’s a matter of skills,” he said.

Russian planes have been brought down previously by terror attacks.

In October 2015, a Russian plane carrying mostly Russian tourists back from vacation in Egypt was brought down by a bomb over the Sinai Peninsula, killing all 224 people aboard. Officials said the explosive device was planted in the plane’s luggage compartment. The local affiliate of the Islamic State group claimed responsibility.

In August 2004, two Russian planes were blown up in the skies over Russia on the same day by suicide bombers, killing 89 people. A Chechen warlord claimed responsibility.

The Associated Press contributed to this report.