Rufus Morrow was at work when he got a phone call with the worst news he could imagine: Shots fired at his daughter's elementary school.

He drove "about 90 mph" to Ronald E. McNair Discovery Learning Academy where 800 or so students in pre-kindergarten through fifth grade had been evacuated Tuesday in an Atlanta suburb. The police chief says a 20-year-old man with an assault rifle and other weapons was able to slip into the school where visitors must be buzzed in by staff.

The suspect, identified as Michael Brandon Hill, held one or two staff members in the front office captive for a time, the police chief said, making one of them call a local TV station. As officers swarmed the campus outside, he shot at them at least a half a dozen times with an assault rifle from inside the school and they returned fire, said DeKalb County Police Chief Cedric L. Alexander. Hill then surrendered. No one was injured.

Morrow said he almost cried as he told his supervisor why he needed to leave.

"Just the mere thought of what happened at that other elementary school happening here, it was just devastating to my soul," he said, referring to the Sandy Hook Elementary School massacre in Connecticut in December that left 26 people dead, 20 of them children.

He wasn't the only one whose thoughts went to that shooting that has dominated arguments over gun control in the U.S.

"I thought it wasn't going to be all right," said his 10-year-old daughter, Dyamond, a fifth-grader. "I thought he was going to come into the building and hurt everybody like what happened at the other school."

Hill is charged with aggravated assault on a police officer, terroristic threats and possession of a firearm by a convicted felon. Police questioned him for hours at headquarters. There was no information on a possible court date. Alexander said police were unsure of Hill's motive and that Hill, who had an address listed in court records about three miles from the school in Decatur, had no clear ties to the school.

A woman answering the phone at a number listed for Hill said she was his mother but that it wasn't a good time and rushed off the phone.

Other parents also feared the worst for their children.

"I was terrified," said Romaine Hudson as she clung to the hands of her 6-year-old and 8-year-old daughters, both of whom are students at the school. "The only thing I could think of when I first heard of this situation was Sandy Hook."

Authorities believe Hill must have walked in behind someone authorized to be there, Alexander said. He never got past the front office, where he held one or two employees captive for a time. School bookkeeper Antoinette Tuff says she was one of the hostages.

In an interview on ABC's "World News with Diane Sawyer," Tuff said she worked to convince the gunman to put down his weapons and ammunition.

"He told me he was sorry for what he was doing. He was willing to die," Tuff told ABC.

She told him her life story, about how her marriage fell apart after 33 years and the "roller coaster" of opening her own business.

"I told him, 'OK, we all have situations in our lives," she said. "It was going to be OK. If I could recover, he could, too."

Then Tuff said she asked the suspect to put his weapons down, empty his pockets and backpack on the floor.

"I told the police he was giving himself up. I just talked him through it," she said.

She told WSB-TV in Atlanta that she tried to keep Hill talking to prevent him from walking into the hallway or through the school building.

"He had a look on him that he was willing to kill — matter of fact he said it. He said that he didn't have any reason to live and that he knew he was going to die today," Tuff said, adding that Hill told her he was sure he'd be killed because he'd shot at police officers. "I knew that if he got out that door he was gonna kill everybody," she said.

Dramatic television footage showed lines of young students racing out of the building with police and teachers escorting them to safety. They sat outside in a field for a time until school buses came to take them to their waiting parents and other relatives at a nearby Wal-Mart. As each bus arrived a couple hours later, cheers erupted in the store parking lot.

Morrow was one of those parents and held his 10-year-old daughter close to him during an interview after the two were reunited.

"My stomach was in my throat for the whole time until I saw her face on the bus," he said.

His daughter, a fifth-grader, told The Associated Press that a voice came over the intercom saying school was under lockdown and instructed students to get under tables. She said her teacher told the class to sing and pray.

"There were a lot of girls crying, I was feeling scared but I didn't cry. I was just nervous," she said.

Tuff called WSB-TV as it was happening to say the gunman asked her to contact the Atlanta station and police. WSB said during the call, shots were heard in the background. Assignment editor Lacey Lecroy said she spoke with Tuff, who said she was alone with the man and his gun was visible.

"It didn't take long to know that this woman was serious," Lecroy said. "Shots were one of the last things I heard. I was so worried for her."

Complicating the rescue, bomb-sniffing dogs alerted officers to something in the suspect's trunk and investigators believe the man may have been carrying explosives, Alexander said. Officials cut a hole in a fence to make sure students running from the building could get even farther away to a nearby street, he said.

The school has about 870 children enrolled. The academy is named after McNair, an astronaut who died when the space shuttle Challenger exploded on Jan. 28, 1986, according to the school's website.

As they waited for their children, many of the parents said they were surprised that anyone could get into the school. Many of them recounted having to ring a buzzer at a door with a camera to get in to drop off or pick up their children.

Debra Hayes, a volunteer lunchroom worker at the school whose granddaughter is a fifth-grader there was leaving the building at 12:40 p.m. after finishing her work. She stopped in the office to check out and saw a young man talking to a secretary but didn't see a gun, she said.

"He said that he was in here because he wanted to speak to an officer. He was not going to hurt no staff, no students or no parent," she said. She didn't think anything was out of the ordinary.

Hayes wished the staff a nice day and walked out. As she was walking away toward home, she heard three gunshots and then sirens.

"I don't know what I'd walked into," she said.

Contributors: Associated Press writers Christina A. Cassidy, Phillip Lucas and Johnny Clark in Atlanta contributed to this report.

Tags: Georgia, school, DeKalb County, shooting, McNair, suspect, McNair Discovery Learning Academy