TORONTO -- Air Canada has rerouted its flights over the Middle East after a Ukrainian plane carrying 176 passengers and crew crashed in Iran killing all on board, including 57 Canadians.

Iranian officials said they suspected a mechanical issue brought down the 3 1/2-year-old Boeing 737-800 jet, which crashed shortly after takeoff at Imam Khomeini Airport in Tehran.

But questions are being raised about the timing of the crash, which happened hours after Iran launched missiles at a U.S. air base in response to the killing of a top Iranian general last week.

Prime Minister Justin Trudeau said the cause of the crash remains unconfirmed and couldn’t rule out the possibility of the plane being shot down.

“It is too early to speculate,” Trudeau said Wednesday, adding that Canada is pushing to be involved in the Iranian-led investigation of the plane crash.

“Our focus today is on the many, many families who are grieving and our focus in the days and weeks to come will be on answering the questions that they have and indeed we all have as to how this happened.”

Air Canada has already rerouted a flight from Toronto to Dubai through Egypt and Saudi Arabia to avoid travelling over Iraq. The airline described the change as “precautionary measures” that will affect its five-times weekly flights to Dubai.

The airline does not offer any direct flights to cities in Iran or Iraq, and Air Canada hasn’t flown its planes over Iranian air space since last summer.

Air Canada is the only Canadian carrier operating in the region, according to Transport Canada.

“Air Canada … has altered its routes to ensure the security of its flights into and over the Middle East,” the department tweeted January 8.

Transport Minister Marc Garneau said satellite data suggested the plane took off in a normal fashion and appeared to be a "very, very standard departure."

"However, we lost contact with it, suggesting that something very unusual happened. But we cannot speculate at this point, there are a number of possibilities," Garneau said at a press conference alongside Trudeau.

Whether or not Canada will be involved in Iran’s investigation into the plane crash is yet to be seen. Canada broke diplomatic relations with Iran in 2012 and closed its embassy in Tehran.

Initially, Ukrainian officials said mechanical failure was believed to be the cause of the crash. They later said nothing has been ruled out.

OTHER PASSENGER JETS DIVERTED

The U.S. Federal Aviation Administration said it was barring American pilots and carriers from flying in areas of Iraqi, Iranian and some Persian Gulf airspace. Transport Canada also said Air Canada would comply with U.S.-led restrictions on commercial flights operating out of the region.

Emirates airline, a partner of WestJet, cancelled scheduled flights between Dubai and the Baghdad on Wednesday for operational reasons.

The flight restrictions reflected fears that the conflict between the U.S. and Iran could ratchet up, following Iranian ballistic missile strikes Tuesday on two Iraqi bases that house U.S. troops.

Those strikes were retaliation for the U.S. killing of Iranian Gen. Qassem Soleimani in a drone strike near Baghdad last week.

At least 500 commercial flights travel through Iranian and Iraqi airspace daily, Dubai-based aviation consult Mark Martin told The Canadian Press.

A raft of European airlines have also changed routes to bypass Iranian airspace.

The Russian aviation agency, Rosaviatsia, issued an official recommendation for all Russian airlines to avoid flying over Iran, Iraq, the Persian Gulf and the Gulf of Oman "due to existing risks for the safety of international civil flights."

Australian carrier Qantas said it was altering its London to Perth, Australia, route to avoid Iranian and Iraqi airspace until further notice.

Singapore Airlines and Malaysia Airlines flights are also rerouted to avoid Iran.

India's Directorate General of Civil Aviation advised Indian commercial carriers to avoid Iranian, Iraqi and Persian Gulf airspace.