Reporting from Islamabad — A Pakistani passenger jet with 152 people aboard crashed Wednesday in a forested ridge outside Pakistan's capital, Islamabad. It was not known whether there were any survivors.

The Airblue airliner, on its way from Karachi to the capital, had been flying through heavy fog and rain when it lost contact with air traffic control and crashed about 10 a.m. local time in the Margalla Hills region, authorities said.

Rescuers were trying to reach the scene amid heavy rain and difficult roads.

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Pervaiz George, spokesman for the Pakistani Civil Aviation Authority, said there were 146 passengers and six crew members aboard.

Mohammed Usman, an official at Benazir Bhutto International Airport, said dozens of relatives of passengers gathered there were crying and desperate to get information about their loved ones.

Saqlain Altaf told Pakistan's ARY news channel that he was on a family outing in the hills when he saw the plane, looking unsteady in the air.

"The plane had lost balance, and then we saw it going down," he said, adding that he heard the crash.

Television footage of the crash site showed smoke and burning debris strewn in a swath cutting through the forest. Rescue helicopters hovered overhead. Fire was visible, and smoke was blowing up from the scene.

Authorities said the flight had originated in Turkey and was on its way to Islamabad via Karachi, Pakistan's largest city. Officials had not determined the cause of the crash.