SANTIAGO, Chile — At least two people were killed and nine others injured Thursday when a train full of passengers collided head-on with another train on a test run just outside Chile’s capital of Santiago. Investigations were underway to determine the cause of the crash, which vaulted one car fully on top of a car from the other train. The eight-car freight train, which was carrying 1,346 tons of copper, was also packed with people, while the other train had 10 workers on board operating a speed test, the state rail company said. Authorities have not identified the two people killed.