(JNS) A Ukranian Boeing 737 passenger jet crashed shortly after takeoff in Tehran, Iran, on Wednesday, January 8, killing all 176 people aboard. Though a spokesman for Iran’s Road and Transportation Ministry claimed that the crash was caused by “technical difficulties,” at least two Kazakh airlines announced that they were considering rerouting or canceling their flights over Iran in light of the fatal crash.

The airliner’s black boxes have been located, but Iran is refusing to hand them over to Boeing, the plane’s manufacturer, for analysis, according to The Times of Israel.