The apartment’s explosion, reportedly caused by a gas leak, produced a violent release of gas and heat. the heat increased the of the air in the room, which means an increase in the air's molecular kinetic energy.

The apartment’s explosion, reportedly caused by a gas leak, produced a violent release of gas and heat. the heat increased the temperature of the air in the room, which means an increase in the air's molecular kinetic energy.

When heat leaves a system, that energy is transferred to its surroundings. Since the air is the surroundings, the heat is transferred to the air increasing the temperature. This causes an increase in the individual air molecules' energy.