DALLAS -- (CBS NEWS) A gunman opened fire on emergency responders treating a gunshot victim in a Dallas street on Monday, critically injuring a paramedic and prompting police to lock down the area until the suspect -- and another person -- were found dead in a local home, authorities said.

Police believe the shooting started as a dispute between the suspect and the gunshot victim, who were neighbors. A police officer who responded to the late-morning shooting in a largely residential area east of downtown was injured and treated at the scene.

The gunman fled before holing up in a house where investigators believe he fatally shot another person before killing himself. A police robot found the two bodies after authorities barricaded entrances to the community for several hours to allow officers to scour the neighborhood, Dallas Mayor Mike Rawlings said during a news conference.

Interim Police Chief David Pughes said police were still interviewing neighbors and witnesses late Monday, but he said officers on the scene were told "it was just a simple dispute between two neighbors that escalated into a shooting."

Pughes said responding officers found the paramedic and the civilian injured, and "took fire from the suspect as they approached." A sergeant arrived as officers were still maintaining cover -- because the shooter was still at large -- and rushed in to pull the injured paramedic to safety.

"He went in alone and he pulled the paramedic out, placed him in his squad car and drove him to Baylor hospital," Pughes said. "We believe ... that as a result of those actions, that paramedic's life was saved."

The paramedic underwent surgery Monday and was in critical but stable condition at Baylor University Medical Center, according to the mayor. Rawlings didn't give details of the paramedic's injuries, but said: "he is going to have to undergo extensive medical treatment to get him back up to par."

The neighbor who was shot also was in intensive care, the mayor said, though other details haven't been released.

No information was released about the second person found dead in the home, including whether the person knew the gunman or if either of them lived in the house.

Dozens of police vehicles swarmed the mostly residential area after the shooting was reported near a local Fire Training Academy. Several people from a nearby neighborhood and some relatives of people who live in the barricaded area gathered at a nearby gas station to await updates from police.

A 33-year-old woman waiting in the shade of a gas station across the street from a police barricade told The Associated Press that her mother lives in the neighborhood and saw SWAT teams arrive Monday.

Brenda Salazar said she was headed to the area to visit her mother when she heard about the shooting on the radio. She called her mother, who told her she didn't hear any shooting but "saw the SWAT guys and police setting up and going into the neighborhood."

Salazar said her mother was OK and was watching the news, "but this stuff happens here all the time."

The Dallas Police Association tweeted earlier Monday that officers responding to an active shooter were "pinned down" by gunfire.

"Please keep the injured EMT and his family in your thoughts and prayers," the Dallas Police Department tweeted.

Texas Gov. Greg Abbott released a statement saying his prayers were going out to all of those affected.

FBI agents and officers with the Bureau of Alcohol, Tobacco, Firearms and Explosives also were in unmarked vehicles waiting at intersections in the neighborhood. Officials from the local fire department and parks department passed out water and Gatorade to officers blocking the roads.

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