LITTLETON, Colo. (AP) — The man accused of wounding two middle school students in a community still haunted by the Columbine massacre had become increasingly erratic in recent weeks, yelling at imaginary friends and complaining that eating macaroni and cheese made too much noise, his father said Wednesday.

Investigators are looking into the bizarre behavior of 32-year-old Bruco Strong Eagle Eastwood as they try to figure out why the unemployed ranch hand allegedly showed up at his old school and started firing at students in the parking lot before being tackled by a math teacher.

Eastwood’s father described his son’s recent strange behavior in an interview with The Associated Press at his ranch outside Denver.

The older man said that his son used to talk to himself a lot, but in the past month, he had begun yelling. The younger man also complained that the refrigerator was too loud and that certain foods made too much noise, his father said.

Others said Eastwood would show up at a nearby gas station to buy cigarettes, but was often 20 or 30 cents short, and would mumble to himself as he read the sports section the newspaper.

‘‘He has problems, but I never thought he’d go to the extent to hurt somebody,’’ said his father, War Eagle Eastwood. ‘‘You can say you’re sorry, but you can’t replace the fear and hurt he’s put in innocent people. He’s put a hole inside of me.’’

As the math teacher was being hailed a hero, officials said the quick response was further proof that the community learned the lessons of Columbine in quickly responding to the shootings. But there was growing evidence the school missed a chance to head off the attack.

Investigators said Eastwood walked through the doors of the Deer Creek Middle School earlier in the day, indicated he was a former student and chatted with teachers.

apparently without drawing much suspicion.

Authorities do they know the nature of his conversations with school staff before he went outside and opened fire with a bolt-action hunting rifle he stole from his father.

Sheriff’s department spokeswoman Jacki Kelley said Eastwood left the building without being asked to do so. She said a school security officer was not at Deer Creek at the time. The officer also has duties at another school, but it hasn’t been determined where he was when the shootings happened, Kelley said.

Asked about the possible security lapse, Jefferson County schools Superintendent Cindy Stevenson said only that there is a sign-in sheet that requires visitors to state their name and the purpose of their visit. She said school officials did not have access to the sheet for Tuesday because the school was closed as a crime scene.

Eastwood was jailed on $1 million bail on suspicion of attempted murder.

Residents were stunned by the thought of a gunman opening fire at a school less than three miles from Columbine High, where two teenagers killed 12 students and a teacher in the nation’s deadliest high school shooting. Parents rushed to the middle school, many unnerved by the sight of youngsters running for lives just like on that day in 1999.

‘‘We thought all of that was behind us,’’ resident Betty Makr said.

David Benke, a 57-year-old teacher and father of three, said he heard one shot and saw the gunman squeeze off a second round as he sprinted toward the man. Another teacher, Norm Hanne, helped subdue the gunman, and Assistant Principal Becky Brown grabbed the gun as it lay on the ground in the parking lot.

Benke, who is 6-foot-5 and has been taking some martial arts training lately, said he told the gunman: ‘‘Look, bud, I’m 6-5. … You’re not going anywhere, so let’s kind of relax till the sheriff’s people get here.’’

Schools in Littleton have gone through extensive emergency drills since the Columbine tragedy, and Benke said he always thought about what he would do if a shooting broke out. ‘‘I said, ‘I hope that I’m capable of doing something about it,’’’ he recalled.

At a news conference, Benke became choked up when he said it bothered him that he didn’t stop the gunman before he shot the second student.

One of the wounded, Reagan Webber, was treated at a hospital and released. The mother of the other victim, Matt Thieu, said he was ‘‘doing well’’ at a hospital.

Benke said that he was simply doing his job and that it was a team effort by the school’s staff. But a Facebook page called ‘‘Dr. David Benke is a Hero!!!!’’ quickly grew to more than 21,000 members, and his actions were discussed on the floor of the Legislature.

‘‘Sometimes that’s just what we need. We need someone to be a hero for us,’’ said state Sen. Mike Kopp of Littleton, who lives in Benke’s neighborhood.

Authorities praised the response as evidence of how ready area schools are to respond to shootings after Columbine, but they also acknowledged the emergency manual does not call for teachers to pounce on gunmen.

Stevenson said Deer Creek’s security precautions involve a single button in a secretary’s office that automatically locks down the school in the event of a shooting. If something happens inside, teachers are to lock doors, get students out of hallways, keep them quiet so as not to tip off any gunmen and stay out of the line of sight, she said. All of that was done Tuesday, Stevenson said.

What Benke did ‘‘is pretty amazing,’’ said Kelley. ‘‘We don’t train people to do that.’’

‘‘Everybody acted, nobody froze,’’ she added.

Eastwood has an arrest record in Colorado dating back to 1996 for menacing, assault, domestic violence and driving under the influence.

Carla Wrisk, a cashier at the Barn Store gas station-convenience store in Hudson, described Bruco Eastwood as a ‘‘weird, very strange guy. He talks to himself a lot.’’

Wrisk said Eastwood would come to buy cigarettes, but was always a little short of money, and she would make up the difference. He would grab a newspaper, look at the sports page and mumble to himself, she said: ‘‘Just a very odd, strange guy. I’m not surprised.’’

In 2005, Eastwood participated in a NASA-funded study in which he spent 10 days in a hospital bed so scientists could study muscle wasting, an affliction experienced by astronauts during long flights, according to a story in the Rocky Mountain News at the time.

He told the newspaper that he had a lifelong dream of being an astronaut and described his occupation to the newspaper as horse trainer working at his father’s ranch. He pocketed $2,200 from the study and was able to spend a week and a half watching DVDs and playing video games in bed.