GRANADA HILLS (AP)  -- A man with a semiautomatic rifle opened fire at a church festival in the San Fernando Valley on Saturday, wounding his ex-wife and two bystanders before several festival-goers grabbed him, wrestled his gun away and held him for police, witnesses and authorities said.

Witnesses described a chaotic scene, with people screaming and running for the exit after gunfire rang out on a grassy field where the festival was being set up at the St. John Baptist de la Salle Roman Catholic parish in Granada Hills shortly before 11 a.m.

Fernando Diaz Jr., 33, was arrested on suspicion of attempted murder. He was being held in the Van Nuys jail in lieu of $1.5 million bail.

Before being taken away Diaz was asked by a reporter with KNX-1070 why he did it. ``I don't really have too much to say about that. It's a personal thing between me and the church,'' Diaz said.

When asked if Diaz has an issue with the church, he responded: ``The church has an issue with me.''

Jeff Sempelsz, a church volunteer was setting up a prize booth when Diaz started shooting.

``I heard bang, bang, bang, bang. It sounded like balloons popping,'' he said. ``I didn't know what it was but I could see the rifle in his hand.''

Diaz's 29-year-old ex-common law wife was wounded in the arm, a 43-year-old man was hit in the chest and a 45-year-old man was wounded in the leg. 

The woman and the man with the leg wound were hospitalized in stable condition. The man with the chest wound was initially listed in critical condition, but later upgraded to stable.

``We believe this is an isolated incident, a domestic-violence dispute,'' said police Capt. Steven Ruiz.

Diaz has a child who attends the church school and has had an ongoing custody dispute with the mother, Ruiz said. Authorities said Diaz was on parole for an unspecified crime, and a restraining order was in place to prevent him from being near the school or his son and ex-girlfriend.

The church's pastor, Father Robert Milbauer, said the festival was about 10 minutes from opening and about 50 volunteers, some accompanied by their children, were busy setting up food and game booths and carnival-style rides when the gunfire began.

``I was walking toward the festival area to say an opening prayer,'' Milbauer said.

Sempelsz said another church volunteer grabbed the man and began struggling for the gun, a .22-caliber rifle made to look like an M-16 assault rifle. The shooter managed to point the weapon at that man's face, Sempelsz said, before he jumped in to help and they managed to wrestle it away.

As he did, several other people, including an off-duty police officer from Burbank, subdued the man. Still another off-duty officer, from Los Angeles, produced a pair of handcuffs and the group held the man until more than a dozen uniformed officers arrived.

A search of the tennis bag used to carry the rifle uncovered 20 bullet rounds, police said.

As the drama was unfolding, security guard William Griffin, who was watching the festival entrance, said dozens of people suddenly came running toward him.

``I heard someone yell, 'Somebody's shooting. Somebody's shooting.' I turned and saw a man with a long rifle. He was very calm,'' Griffin said.

The guard said he quickly began herding people into the church, then began locking the doors. The man who had been shot in the leg calmly limped in with the others, he said.

The annual festival was shut down for the day, and grief counselors arrived at the church to meet with the children and others.

The church and school are in an ordinarily peaceful, multiethnic, middle-class residential neighborhood in Granada Hills -- not far from the historic San Fernando Mission. The congregation counts about 4,200 families as members.

Until Saturday the 21-year-old event had never been the scene of violence, said Jerry Eckel, 62, a secretary in the religious education department.

``I'm just really shocked because I have been a member of the parish since I was 16 years old,'' she said. ``I grew up there. It's home to us.''