An explosion in the center of the northern Italian city of Milan set several vehicles on fire. The blast came from a van carrying oxygen cylinders, the city's mayor said.Italy Photo Press/IMAGOSeveral vehicles were in flames after an explosion rocked the center of Italy's second city Milan, according to reports on Thursday.The incident appears to have been the result of an accident and there are no known fatalities. Officials said at least one person was injured as a result.Mayor Giuseppe Sala told reporters the van where the blast originated was carrying oxygen cylinders and that the explosion was not due to terrorism or crime.What happened?Witnesses in the city's Porta Romana neighborhood reported the loud explosion at about 11:45 a.m. (09:45 UTC) and saw a plume of black smoke.