"He's got a gun! Get down!"

Christina Coley and others jammed on the CTA bus hit the floor as a teen fired round after round.

Yet Coley, 17, said she remained calm amid chaos -- she didn't even know a bullet had pierced her chest and left arm until she looked down at her blood-soaked hooded shirt.

"I didn't feel no pain," Coley said. "They just said, 'See if you're shot.' I'm just happy I'm alive."

Coley -- a junior at Percy L. Julian High School who was on her way home -- was able to walk off the bus on the South Side. She was whisked to a nearby hospital in a stranger's car and released hours later.

Blair Holt, who sat across the aisle from Coley, was also rushed to the hospital but died during surgery. A bus videotape shows Blair -- the 16-year-old son of a Chicago Police officer and fire captain -- turning his body as if to protect another girl. Three other students were wounded.

Holt's father told reporters he believes his son was trying to shield the girl from the gunman's bullets when he died.

"I'm so proud of him," said Ronald Holt, who has worked on gang crimes. "He gave his life to save another life. . . . I taught him courage. He was a good kid. I miss him."

Principal IDs suspect
Police said the gunman boarded at the front of an eastbound No. 103 bus at 103rd and Halsted about 3:20 p.m. Thursday and started shooting, striking two males and three females, all of whom were Julian students. The driver pulled over two blocks later at Lowe, and the shooter fled.

The suspected gunman, believed to be a 16-year-old gang member, fled into the South Side Washington Heights neighborhood and remained at large Friday.

Police swarmed the neighborhood searching for the former Julian student, identified by the principal after he viewed surveillance photos from the bus.

Top police brass maintained a presence at the school all day, and pastors from local churches walked in on their own to comfort their congregants.

Investigators were still sorting out why the gunman opened fire, but Julian students knew him as a troublemaker.

Police: Gunman kicked out
The suspect, they said, was kicked out of school this year. He regularly dropped by the school with other gang members to stir things up, they said.

"He's the cause of everything," said a junior.

Students said Blair Holt was a popular junior known for rapping -- in the bathroom, the lunchroom or wherever he could tell his stories about girls, cars and life. He looked good in pink and was well-liked by girls.

"He was so funny. He told a lot of jokes," said Alyssa Wadlington, 17. "He was cool with everybody."

There was heavy police presence in the neighborhood where the suspect lived, with investigators showing his picture to neighbors.

20th CPS student killed
A woman who identified herself as the suspect's sister came out of her house to defend her brother. She doesn't believe he is involved in the shooting.

"He just wouldn't get messed up in something like this," she said, but added that her brother had not been home since Wednesday night -- an unusual occurrence.

Holt was the 20th Chicago public school student killed this year, said Chicago Public Schools CEO Arne Duncan.

"I'm furious and it's heartbreaking," Duncan said. "What happened here yesterday is just absolutely staggering."

Christina's mother, Dolores Coley, said her family has seen tragedy only through natural death or health problems, "but not by somebody trying to take our baby out."

She's glad her oldest child of three is alive and is praying for the Holt family. "God bless him because now he's gone," she said. "And it's so sad."