DALLAS (AP) A 16-year-old girl and her boyfriend have been charged with capital murder in the fatal shooting of a grandfather who tried to protect his family from masked intruders in his Dallas home, police said Tuesday.

The girl, who was not identified, was arrested along with 17-year-old Jose Alfaro at his apartment Monday night after a two-hour "negotiation" to have them surrender, Dallas Police Lt. David Pughes said. They are accused in the killing of 66-year-old Lorenzo Moreno early Sunday.

Authorities believe the girl had fallen out with Moreno's granddaughter and went to his house to confront her. Police say the girl, Alfaro and other teenagers entered the house and an argument quickly escalated. Moreno was shot, and his granddaughter, wife and son were beaten. A TV was stolen.

"I think that based on all the information we have, the whole offense itself was generated because of the feud between these two," Pughes told reporters.

He said the girl was in juvenile custody while Alfaro, who was charged as an adult, was being held on $1 million bond at the Dallas County jail. He didn't have an attorney listed in online records.

Four suspects are believed to be at large. Pughes said he didn't know who shot Moreno or who was carrying a weapon.

"When you have as many as six suspects, we're going to need to talk to each and every one of them before we can figure out what each person's role was in that offense," Pughes said.

Pughes said he didn't believe the girl had pulled the trigger, but that she was responsible for the group going to the Moreno home. He declined to say why the two girls were fighting, but said their feud likely had several reasons.

Ricky Moreno, Lorenzo's son, told Dallas television station WFAA that he tried to fight off the group of intruders and was beaten in the process.

"I did my best," Moreno said. "I tried my best, and (I) guess when he saw me beat up the first two, that's when he came, the guy with the gun came and hit me on my head right here."