WEST, Texas (AP) ― A massive explosion at a fertilizer plant near Waco on Wednesday night injured dozens of people and sent flames shooting into the night sky, leaving the factory a smoldering ruin following a blast that damaged buildings for blocks in every direction.

The explosion at West Fertilizer in the town of West happened shortly before 8 p.m. local time and could be heard as far as 72 kilometers away.

Tommy Muska, West’s mayor, said at a news conference three hours after the explosion that he didn’t yet know how many people had been injured or killed. He said buildings in a five-block radius from the plant were severely damaged by the explosion.

Among the damaged buildings was the West Rest Haven Nursing Home, from which first-responders evacuated 133 patients, some in wheelchairs. “We did get there and got that taken care of,” Muska said.

Information was hard to come by in the hours after the blast, with even Texas Gov. Rick Perry saying state officials were waiting for details about the extent of the damage.

“We are monitoring developments and gathering information as details continue to emerge about this incident,” Perry said in a statement. “We have also mobilized state resources to help local authorities. Our thoughts and prayers are with the people of West, and the first responders on the scene.”

Aerial footage showed fires still smoldering in the ruins of the plant and in several surrounding buildings, and people being treated for injuries on a flood-lit local football field, which had been turned into a staging area for emergency responders.

Debby Marak told The Associated Press that when she finished teaching her religion class Wednesday night, she noticed a lot of smoke in the area across town near the plant, which is near a nursing home. She said she drove over to see what was happening, and that when she got there, two boys came running toward her screaming that the authorities ordered everyone out because the plant was going to explode.

She said she drove about a block when the blast happened.

“It was like being in a tornado,” Marak, 58, said by phone. “Stuff was flying everywhere. It blew out my windshield.”

“It was like the whole earth shook.”

She drove 10 blocks and called her husband and asked him to come get her. When they got to their home south of town, her husband told her what he’d seen: a huge fireball that rose like “a mushroom cloud.’’

The explosion caused the roof of what appeared to be a housing complex of some kind to collapse. In aerial footage from NBC’s Dallas-Fort Worth affiliate, KXAS, dozens of emergency vehicles could be seen amassed at the scene. Entry into West was slow-going, as the roads were jammed with emergency vehicles rushing in to help out.

Authorities set up a staging area on a flood-lit high school football field, where the injured were being treated or taken to area hospitals via road or helicopter.

Glenn A. Robinson, the chief executive of Hillcrest Baptist Medical Center in Waco, told CNN that his hospital had received 66 injured people for treatment, including 38 who were seriously hurt. He said the injuries included blast injuries, orthopedic injuries, large wounds and a lot of lacerations and cuts. The hospital has set up a hotline for families of the victims to get information, he said.

Robinson did not immediately return messages from the Associate Press.

American Red Cross crews from across Texas were being sent to the site, the organization said. Red Cross spokeswoman Anita Foster said the group was working with emergency management officials in West to find a safe shelter for residents displaced from their homes. She said teams from Austin to Dallas and elsewhere are being sent to the community north of Waco.

A West Fire Department dispatcher said any casualties would be transported to hospitals in Waco, north of Austin, the state capital.

The explosion knocked out power to many area customers and could be heard and felt for miles around.

Brad Smith, who lives 45 miles north of West in Waxahachie, told the station that he and his wife heard what sounded like a thunderclap.

Lydia Zimmerman, told KWTX that she, her husband and daughter were in their garden, 20 kilometers from West, when they heard multiple blasts.

“It sounded like three bombs going off very close to us,” she said.

Rafael Abreu, a geophysicist with National Earthquake Information Center of the U.S. Geological Survey, said the explosion did not register on a seismograph because most of the blast’s energy dissipated in the atmosphere.

In 2001, an explosion at a chemical plant killed 31 people and injured more than 2,000 in Toulouse, France. The blast occurred in a hangar containing 300 tons of ammonium nitrate, which can be used for both fertilizer and explosives. The explosion came 10 days after the Sept. 11, 2001, terrorist attacks in the U.S., and raised fears at the time it was linked. A 2006 report blamed the blast on negligence.