Officials say Iran mistakenly shot down the Ukranian plane that crashed shortly after taking off from an Iranian airport, Wednesday.

European security told CNN they believe reports suggesting that the International Airlines Boeing 737-800 was shot down by an Iranian surface to air missile in error are credible. 

CNN says though nothing is officially confirmed, the aforementioned working theory is deemed credible based on an analysis of information from satellites, radar, and electronic data. 

At this point, Iran's Civil Aviation Organization head, Ali Abedzadeh, said it would not give the flight data recorders to Boeing or to the United States after they were found, Wednesday.

One of the officials said the U.S. is working closely with the Canadians on the intelligence.

The Ukrainian International Airlines (UIA) flight PS752 came down only minutes after takeoff from Tehran on Wednesday local time, killing all 176 on board, including dozens of Iranians and Canadians.

The plane was headed for Kiev, where 138 of the passengers were expected to take a connecting flight to Canada. Ukrainians, Swedes, Afghans, Germans and British nationals were also aboard.