21.   Leaves of a plant burst into flames when sparks from a camp stove ignited them, he says.

22.   Methane can build up easily in poorly ventilated mine shafts and a spark can ignite it.

23.   Police speculated that a spark may have ignited it.

24.   The cause of the accident was being investigated, but Deputy Public Health Minister Tinawat Marupitak said he suspected sparks had ignited alcohol used in the production process.

25.   The gas then leaked into the water main and collected at a nearby subway construction site until a spark ignited it an hour later.

26.   They were not violent yet it was clear what any spark might ignite.

27.   Witnesses said the blaze appeared to have been ignited by sparks from welding equipment being used for routine repair work.

28.   A spark ignited fire-crackers stored in the factory in Chiyyaram town, killing six workers inside the unit.

29.   But Pakistan has repeatedly warned just a small spark could ignite a large-scale conflict.

30.   It is thought the fire started when sparks from a machine ignited dense glue fumes, the news agency said.