Iran's initial report says Ukrainian jet was on fire before crash:

Ukraine declares national day of mourning, president cautions against speculation around cause.  A Ukrainian airliner was on fire immediately before it crashed southwest of Tehran, killing all 176 on board, according to an initial report by Iranian investigators.

The Ukrainian International Airlines Boeing 737-800, flying to Kyiv and carrying mostly Iranians and Iranian-Canadians, crashed shortly after taking off on Wednesday from Tehran's Imam Khomeini airport.

The report by Iran's civil aviation organization cited witnesses on the ground and in a passing aircraft flying at high altitude as saying the jet was on fire while still aloft.

The three-year-old jet, which had its last scheduled maintenance on Monday, encountered a technical problem shortly after take-off and started to head toward a nearby airport before it crashed, the report said.

Mourning of Ukrainian plane carsh

The technical problem was not specified in the report, which also said that there was no radio communication from the pilot and that the aircraft disappeared from radar at 2,440 metres.

The crash happened hours after Iran launched missile attacks on U.S.-led forces in Iraq, leading some to speculate that the plane may have been hit. n Kyiv, Ukraine's President Volodymyr Zelensky said the government was considering several possible causes of the plane crash.

In a television statement, Zelenskiy asked people to refrain from speculation, conspiracy theories and hasty evaluations regarding the crash. He also declared Jan. 9 a day of national mourning. He said that he would speak by telephone with the Iranian president to step up co-operation into the reason for the crash.

The Ukrainian airliner took off from the Tehran airport at 6:12 a.m. local time and was given permission to climb to 26,000 feet, the report said. It crashed minutes later. Bodies and body parts recovered from the site of the crash have been taken to the coroner's office for identification, the report said. Smouldering debris, including shoes and clothes, were strewn across a field where the plane crashed on Wednesday, where rescue workers in face masks laid out scores of body bags.

Ukrainian authorities have said those on board included 82 Iranians, 63 Canadians, and 11 Ukrainians. The Tehran-Toronto via Kyiv route was a popular for Canadians of Iranian descent visiting Iran, in the absence of direct flights.