Authorities say two firefighters and two civilians were injured in a powerful explosion that shook a northwest Portland, Oregon, neighborhood as utility workers were repairing a damaged gas line.

Lt. Rich Chatman, spokesman for Portland Fire and Rescue, said there were no fatalities in the Wednesday morning incident that he described as a "significant" explosion. An earlier tweet from the fire department said three firefighters were injured. Chatman said the situation was in flux and authorities were still gathering information about the blast.

The explosion was felt throughout the neighborhood and smoke was seen billowing from a building.

Fire officials called in additional resources after the initial response to deal with the situation.