Video - Breaking News Videos from CNN.com Pakistan observed a day of mourning Thursday for the 152 people who died when a passenger plane went down in the outskirts of the capital Islamabad the day before. The crash Wednesday was the second deadliest involving a Pakistani airline, officials said. Prime Minister Syed Yusuf Raza Gilani cancelled a cabinet meeting, and flags across the country flew at half-staff. The Airblue plane was headed to Islamabad from the sea port city of Karachi when it crashed in a hillside while trying to land. The deadliest occurred in September 1992 when a Pakistan International Airlines Airbus crashed into a mountain in Nepal, killing all 167 people on board, the Associated Press of Pakistan reported. Officials do not know if weather played a factor in the crash Wednesday. Recovery crews have yet to find the plane's voice and data recorders. Pakistan is in the midst of the annual monsoon season when rain sweeps across the subcontinent from June until September. The Airbus A321 was carrying 146 passengers and six crew members, the airline said. The U.S. Embassy in Pakistan said two of the people aboard were U.S. citizens.