At least 21 people were injured in an explosion inside a train carriage here on Thursday night, RT.com reported.A local TV news Channel reported that just before 10 p.m. local time there was a loud bang in the sixth carriage of a crowded commuter train, which then quickly became engulfed in flames. The Straits Times and several other local media said there were three explosions.A local newspaper cited eyewitnesses as saying that they saw a man in his 40s walk inside the carriage, put down a 15-20 cm tube-like object and quickly exit the train. National Police Agency Director General Chen Kuo-en has confirmed that the explosion was likely caused by a "firecracker-like device". However, police refused to call the incident a terrorist attack.