The suspect in a San Diego-area grade school shooting that left two young girls injured was not cooperating with investigators, police said, and the man's neighbors described strange behavior in the months before the shooting.

Brendan L. O'Rourke, 41, was in custody Saturday for investigation of six counts of attempted murder and numerous weapons violations.

Carlsbad police Lt. Kelly Cain said O'Rourke was refusing to answer questions and police did not know what he intended to do or why he opened fire, but they believe he acted alone.

"He is not cooperating with the investigation," Cain said Friday night. "He probably has some mental health issues."

O'Rourke's neighbors told the San Diego Union-Tribune in a story posted on its website Saturday that he often screamed obscenities and racial epithets alone in his apartment and they frequently called police.

Vickie Rowe-Mitchell, who lives in the apartment beneath O'Rourke, said he would curse and scream the N-word for hours late at night, and said his stomping and banging was so loud her ceiling fan would shake and parts of her ceiling would fall.

"I always felt in my head he was going to do something bad," she told the newspaper. "It was just a feeling in my soul."

None of the residents of Canyon Creek Apartments knew what he did for a living.

Another neighbor, Ashley Johnson, said she had seen O'Rourke on Friday morning just a few hours before the shooting.

"I was opening my door and she was just leaving," Johnson said. "He closed his door really fast and there was this weird chemical smell. It smelled really weird in his house."

Police said a propane tank was found near Cain's car and a gas canister was found at a playground at the school after the shooting.

At about noon Friday, police said O'Rourke parked his car, jumped a fence and opened fire on the crowded playground, hitting a 6-year-old and 7-year-old in the arms before construction workers tackled him.

The girls were taken by helicopter to Rady Children's Hospital. The injuries were not life-threatening and they are expected to make a full recovery, Cain said.

Second-grader Caden Smith said he ended up in a classroom with injured girls.

"One, her arm was covered in blood and all you could see was red," Caden told the North County Times. "The other, there wasn't that much blood."

Third-grader Tommy Donahue said he was playing outside when he heard what sounded like firecrackers.

"Once the noise happened, everybody decided to scream and run for the classroom," Tommy told the newspaper as he stood next to his mother. "I felt safe in the classroom."

O'Rourke was briefly taken to Scripps Memorial Hospital then booked at the Vista Jail.

Sheriff's deputies reached by phone Saturday said they did not know if he had hired a lawyer.

Parents, like professional surfer Scott Chandler who lives across the street, shudder to think of what could have happened if the man had not been stopped.

"He had some kind of mission he was on and he didn't complete it," Chandler said.

Chandler was repairing a Jet Ski in his driveway when he heard two loud bangs and saw children running and screaming. He ran downhill in his flip-flops and took cover behind some tall Eucalyptus trees while he called 911. He saw several men struggling on the side of the road.

He approached the crowd after realizing the school's construction workers were pinning down the man. Chandler said he saw bullets fall out of the suspect's pocket.

"His face was in the dirt, his teeth were in the dirt, and he just grunted," Chandler said.