Two people were killed and 44 injured when two commuter trains collided head-on in Britain’s second fatal rail crash in three days. Scotrail, a branch of the state-owned British Rail, said the trains were traveling at less than 30 m.p.h. in opposite directions when they collided outside Bellgrove Station in Glasgow. At least two cars of the trains, carrying about 70 passengers, derailed. The cause of the accident was not immediately known. A crash Saturday on the outskirts of London killed five people and injured 94. Last Dec. 12, three trains crashed near a busy south London junction during rush hour, killing 35 people. That accident was blamed on a signal failure.