Flags are flying at half-mast on government buildings around Ukraine, Wednesday, and all sporting events and entertainment have been canceled, as the country pauses to remember those killed in Tuesday's fiery plane crash - believed to have been caused by severe weather.

Russia will mark its own day of mourning, Thursday.

The Tupolov-154 - owned and operated by Pulkovo Airlines - was full of mostly Russian vacationers, returning home to Saint Petersburg from the Black Sea Resort, Anapa. Early into the flight, the plane encountered stormy weather and disappeared from radar contact. It then attempted an emergency landing, amid reports of a fire onboard. The landing gear failed and the craft went down in a remote field, some 45 kilometers north of Donetsk.

The search for the planes black boxes resumed at dawn and proved successful several hours later, according to Russian transport minister Igor Levitin.

Mr. Levitin says investigators are now in custody of both black boxes and have already begun analyzing recordings of conversations between the pilots and Ukrainian air traffic control.

Earlier, Russian Prosecutor General Yuri Chaika announced the opening of a criminal inquiry into a possible violation of safety rules. Pulkovo Airline officials say the plane, built in 1992, was properly serviced and maintained.

Meanwhile, dazed relatives have begun making their way to the Ukrainian crash site. There, it is reported many will be required to provide DNA to help identify their loved ones. Only 30 bodies have been recovered, so far.

Many families are still trying to come to terms with their grief and are turning to the emergency crisis centers set up by the government. One such center is in Anapa, where Dr. Viktor Kosenko is on staff.

Dr. Kosenko says many of the people who lost family members and loved ones in the crash are in shock, unable to comprehend all that has happened. He says they need immediate counseling and, for some, possible medical attention.