71.   Investigators later determined the blast was caused by gasoline that had leaked out of an underground pipeline into the sewer system.

72.   It is not clear what caused the blast.

73.   It gave few details and did not say if the blast was caused by a bomb or believed related to the anniversary.

74.   Israel television said the blast was apparently caused by a car bomb.

75.   It was not clear if the blast was caused by a bomb or an accident.

76.   It was not immediately clear what caused the blast, the agency wrote.

77.   It was not immediately known what caused the blast at the government-run High Energy Materials Research Laboratory.

78.   It was not immediately known what caused the blast at the Kati garrison.

79.   It was not immediately clear what caused the blast and the Israeli army said it was checking the report.

80.   It was not immediately clear what caused the blast, a rare violent incident in the normally placid city of Vientiane.