Authorities in Davenport, Iowa, are carrying out search and rescue operations after a six-story apartment building partially collapsed on Sunday, leading officials to find gas and water leaks amid the wreckage.

"This is an active scene, we will continue to work, continue to evaluate, and with the whole purpose of trying to find people and trying to get them out," said Davenport Mayor Mike Matson at a news conference Sunday night.

Seven people have been rescued from the building and more than a dozen others self-evacuated and were escorted out, Davenport Fire Chief Michael Carlsten said.

Officials did not say how many people are still unaccounted for or how many residents have been displaced by the building damage. The area will remain closed as search efforts and an investigation into the collapse are underway, officials said.

The cause of the collapse has yet to be announced.

Once on the scene, emergency crews detected a large natural gas leak and water leaking from each floor of the building, officials said. The utilities have since been secured and rescue crews are resuming search efforts for people unaccounted for.

During the news conference, the city's Neighborhood Services Director, Richard Oswald, confirmed that the building's owners had current permits for repair work to be done on the exterior wall.

Both Matson and Carlsten noted they had concerns about the integrity of the building.