A gas explosion in a D.C. apartment building left a woman seriously injured Friday morning.

Around 9:30 a.m., D.C. firefighters responded to the third floor of a four-story apartment building near the intersection of Columbia Road and Harvard Court in the Columbia Heights section in Northwest after reports of a gas explosion.

A woman inside the apartment was seriously injured and had to be hospitalized, authorities said.

The building was evacuated and all gas lines were secured.

Later Friday, officials said investigators had determined the blast was an accidental gas explosion.

Below is a map of the area where the gas explosion took place: