An early morning blaze onboard a mainland vessel at Hong Kong's Yau Ma Tei typhoon shelter has left 18 people injured, including 12 firemen and six sailors, Hong Kong China News Agency reported Tuesday.

The fire occurred at 1 a.m. on Tuesday, triggering a level-3 fire alarm. The local fire department sent 24 trucks and 140 firemen to put it out.

Several explosions were heard during the blaze, which took five hours to extinguish.

The ship, carrying a cargo of hardware waste, is reportedly from Guangzhou, south China's Guangdong Province. The cause of the fire is still under investigation.