PORTLAND, Ore. — Firefighters who responded to what should have been a routine call about a gas leak in Portland, Ore., likely saved lives when they decided to evacuate the building and pulled a fire alarm to warn holdouts just minutes before a powerful explosion, officials said.

The blast shortly after 9:30 a.m. Wednesday in a popular shopping district injured eight people and ignited a fire that sent a plume of smoke over the heart of the city.

Three firefighters, two police officers and three civilians were hurt, and one of the firefighters underwent hours of surgery for a broken leg, Portland Fire Chief Mike Myers said at an afternoon news conference. None of the injuries appeared to be life-threatening.

City officials said a catastrophe was averted by speedy work from firefighters and police who cleared the area of people before the blast.

“There are a lot of people alive” who might not be “but for the excellent work by our first responders,” Mayor Charlie Hales said.

A building that housed a bagel shop and a beauty salon in the popular NW 23rd Street shopping district was reduced to rubble, and its smoldering roof was splayed across the road.

The walls and windows of a nearby building were blown out, debris was everywhere and businesses three blocks away reported that their doors flew open from the force of the blast.

Firefighters swarmed the scene and dumped water from ladder trucks onto the smoking wreckage. Dozens of business owners and residents were still barred from the area as night fell Wednesday.

NW Natural released a timeline saying the explosion occurred at 9:38 a.m. — a time when many businesses were still closed.

Portland’s NW 23rd Street is packed with boutiques, bars and restaurants. Many are on street level with pricey apartments on the upper levels and a day care facility in the vicinity.

The utility said it got a call at 8:55 a.m. saying a construction crew had hit a gas line. Authorities and utility workers responded in 15 minutes and evacuated the building, NW Natural CEO David Anderson said at the new conference.

People in the neighborhood reported smelling gas as they were evacuated.

The utility hasn’t determined what caused the gas to ignite, Anderson said at the news conference that it was an extremely rare event that required a certain amount of ambient gas, an enclosed space and an ignition source.

Authorities credited firefighters and police officers with saving lives by reacting quickly to evacuate the building.