A mother and son have been killed after a fire broke out inside their home in Seoul’s Mapo District.

The fire started in the 14th-floor apartment unit around 8 a.m. Sunday, where the son in his 20s was found dead and the mother in her 60s without vital signs.

The mother was later pronounced dead, while the father in his 60s suffered burns and some ten other residents in the building were injured.

The fire was put out some two hours later, and it is believed to have taken longer in the absence of a sprinkler system on the 14th floor, which was not required by law when construction of the building was completed 27 years ago.

The police and fire authorities began an on-site scientific analysis on Monday to determine the exact cause of the fire.

Authorities are reportedly focusing on a statement from a family member indicating the fire started after a battery for an electric scooter exploded while being charged inside a room.