CLEVELAND — A gunman opened fire in a downtown high school today before killing himself, and five people were taken to a hospital, authorities said.

After the shooting, shaken teenagers called their parents on cell phones, most to reassure but in at least one case with terrifying news: “Mom, I got shot.”

Mayor Frank Jackson said three teenagers and two adults were hurt. He said the children were in “stable, good condition,” and the adults were in “a little elevated condition.”

Police said SuccessTech Academy had been secured and that the lone suspect had fatally shot himself. Students said he was enrolled at the alternative school but did not attend class today.

A student, Doneisha LeVert, who hid in a closet with two other students after she heard a “Code Blue” alert over the loudspeaker, said the shooter had threatened students Friday.

“He’s crazy. He threatened to blow up our school. He threatened to stab everybody,” she said.

Ronnell Jackson, 15, said he saw a shooter running down a school hallway.

“He was about to shoot me, but I got out just in time,” he said. “He was aiming at me I got out just in time.”

Tammy Mundy, 38, who has a son and daughter at the school, told The Plain Dealer that her daughter called when the shooting started.

“She said, ‘Mom they’re shooting in here, kids are running out, I’m hiding in the closet,'” Ms. Mundy told the newspaper.

Then she called her 18-year-old son, Darnell Rodgers, on his cell phone, and he told her he had been shot in the arm.

“He said, ‘Mom, I got shot,'” Ms. Mundy told the newspaper.

Mr. Rodgers’s girlfriend, 17-year-old Lateisha Riddlehill, who hid in a bathroom during the shootings, confirmed that Mr. Rodgers had been shot in the elbow. She said he told her he was going to be fine.

The mayor said two boys, ages 14 and 17, were hurt, as were two men, ages 42 and 57, and a 14-year-old girl he said fell and hurt her knee while running out of the school. It was not immediately clear if the 17-year-old he referred to is Mr. Rodgers.

The 57-year-old is a teacher and was in good condition, a spokeswoman for Metro Health Medical Center, Eileen Korey, said. She said the older teenage student was in stable condition, and that conditions on the other patients were not being released.

Students stood outside the building, many in tears, hugging each other, and on cell phones. Others shouted at reporters with TV cameras to leave them alone. Family members also stood outside, anxiously waiting for their children to be released.

“I’m scared. I’m hoping no more people got hurt,” Ronnell Jackson said.

The shooting occurred across the street from the FBI office in downtown Cleveland, and students were being sent to the FBI site.

“There are a lot of emergency vehicles,” a spokesman, Scott Wilson, said. “They’re just trying to sort things out right now.”

Mr. Wilson said he had no information on the shooting.

SuccessTech Academy is an alternative high school in the Cleveland city school district that emphasizes technology and entrepreneurship. It is housed on several floors of the district’s downtown Cleveland Lakeside Avenue administration building.

The school has about 240 mainly black students with a small number of white and Hispanic students. All the students are considered poor under federal poverty guidelines.

The school, opened five years ago, ranks in the middle of the state’s ratings for student performance. Its graduation rate is 94%, well above the district’s rate of 55%.