11.   Passengers and crew members overpowered him after he tried to ignite a wire leading from his sneakers, which contained explosives.

12.   Police were on high alert, however, searching every visitor who entered the City Hall building and using dogs to sniff packages that might contain explosives.

13.   Red, for example, corresponds to a substance that may contain chemical explosive.

14.   The authorities in San Francisco also had a scare when security guards at the airport found an unattended piece of luggage that they thought might contain explosives.

15.   The device that looked like a pipe bomb did not contain explosives.

16.   The shells contained no explosives, in what was apparently an attempt by Israel to minimize the danger of civilian casualties.

17.   Though men in a van were detained, the vehicle did not contain explosives.

18.   Police said the bear Dag had used to hijack the plane contained no explosives.

19.   Police said they could not immediately confirm whether the car contained explosives.

20.   Police supervised the explosion of the vehicle, which they determined did not contain explosives.