DETROIT, Michigan - Five people were injured by an explosion at a General Motors laboratory near here during tests on prototype lithium-ion batteries for electric cars.One was taken to a local hospital. Fire Department officials reported that hydrogen sulphide fumes caused the blast in the battery laboratory.A man who was concussed and took chemical damage to his skin was outside the containment area where tests were being conducted on a prototype battery.EVACUATION CALLEDJim Fouts, mayor of the town of Warren, said: "It was a major explosion. At least one 20cm thick door was blown out. What could have been a catastrophic event was not so because of the quick work of the fire crews and GM officials."The explosion blew out at least three windows and, according to Fouts, about 80 people in the building were evacuated.GM said the incident occurred: "The explosion was in a test chamber at the General Motors Alternative Energy Centre during extreme testing of an experimental battery. Gases from the battery cells were released and ignited in the enclosed chamber. The battery itself was intact."The battery being tested and the incident have no connection with the Chevrolet Volt or any other GM production vehicle."The Volt has been highlighted as a centrepiece in GM's push for better fuel-efficient vehicles.Fouts said he was told that at no time was hazardous waste a threat to workers or the community near the GM Tech Center.People familiar with the matter said the battery was being developed for future electric vehicles.GM spokesman Greg Martin added: "It's entirely premature to speculate on the cause or to characterise the nature of the incident."