Two Italian commuter trains collided Tuesday in the southern region of Puglia, killing 22 people, a railway police official said, as rescue crews searched through wreckage for those who may be trapped.

Commander Giancarlo Conticchio told Sky TG24 said the number of injured is 43, and that there could still be changes in the final toll.

He said, "surely one of the two trains shouldn't have been there. And surely there was an error. We need to determine the cause of the error."

The two trains, each with four cars, collided head-on near the town of Andria on a line with just a single track, according to news agency ANSA and Sky TG24.

"The rescue is complicated because this happened in the middle of the countryside," a fire service spokesman said.

A still photo of the crash showed cars crumpled together and forced off the tracks at sharp angles. News reports said rescue workers were pulling victims from the rubble, including a small child who was alive. Video images showed ambulances responding to the scene with other rescue workers.

"Some of the cars are completely crumpled and the rescuers are extracting people from the metal, many of them injured," Riccardo Zingaro, the chief of the local police in Andria, told ANSA at the scene.

National police and Carabinieri couldn't immediately give details about the extent of the crash, saying they were in the middle of responding.

Italy's prime minister, Matteo Renzi, said the train crash "is a moment of tears" and pledged not to stop until a cause was determined.

Renzi spoke in Milan but was returning to Rome to monitor the situation.

The mayor of Corato, site of the head-on train crash in Italy's southern Puglia region, says the scene is horrific but that rescue work is ongoing with firefighters, civil protection officials and volunteers.

Mayor Massimo Mazzilli told Sky TG25 that rescue workers had just pulled out a passenger alive and were poised to extract a second one.

On his Facebook page, Mazzilli posted photos of the mangled steel trains that collided Tuesday.

He wrote: "It's as disaster, as if an airplane fell. Rescue workers and civil protection is on the scene, but unfortunately there are victims!"

The Associated Press contributed to this report