ARLINGTON -- Makita Pinion sat in a sport utility vehicle Thursday morning, staring across the intersection where her brother Clarence "C.J." Robinson was fatally shot Wednesday, a young man who just wanted to help out after a bizarre multivehicle wreck."He was living over there with a roommate," said Pinion, 22, pointing to a nearby apartment complex. "He was on the way to pick up my son at school. He was walking, and somebody told me C.J. heard one of the babies [in the crash] crying. And he went over to try and help, and the man just shot him in the street."Arlington police and witnesses say Robinson, 18, was shot by Thomas Lester Harper, 27, who caused the crash at North Collins Street and Brown Boulevard that killed a pickup driver.After hitting the pickup and other vehicles, Harper's Chevrolet Tahoe came to rest on a curb with his twin toddlers in the back seat. Witnesses say Harper was "ranting and raving" as people, including Robinson, approached the SUV to help.Seconds later, Robinson lay dead in the street."He shot him for no reason at all," Pinion said. "He was a good Samaritan, and got his life taken."Police said Thursday that Harper likely didn't know his victims. They discounted road rage as an explanation for the rampage."We're working several avenues, including toxicology, to determine what may have led the suspect to take these actions," police spokeswoman Tiara Richard said.Harper remained in the Arlington Jail on Thursday facing charges of murder, intoxication manslaughter and endangering a child. Bail is set at $555,000.'A good brother'Pinion said Robinson was the second brother she lost in five days; both were gunshot victims.She said her other brother was killed in New Orleans, but she declined to elaborate on the details of his death.A relative from New Orleans who identified herself only as Linda, said family members were missing the funeral in New Orleans because they had to deal with Robinson's death."He was a good brother," Pinion said. "He loved to help other people, and this was a prime example of his character."Arlington school officials said Robinson had attended Lamar High School until October, when he withdrew. Before moving to Arlington, he had attended schools in a New Orleans suburb.Friends described Robinson as a friendly teen who loved to dance and make people laugh. Former classmates at Lamar were in shock over the news but not surprised that Robinson was trying to help someone."If he saw you sad or crying in the hall, he'd stop and pat you on the back or say something funny to try and make you feel better," Lamar student Dia McMillian said.Friends said he quit school and picked up as many extra shifts as he could at a Potbelly Sandwich Shop to pay for a GED program.Though he liked football and had other interests, dancing was his passion, friends said."The way he danced, it was like he was just always feeling it," said Derrick White, a senior at Lamar.Co-workers at Potbelly said Robinson often shot videos of his dancing. That didn't bother general manager Kesha Riley, who said he was a hard worker who always made customers and co-workers smile."He would often break out into a dance and I'd say, 'Yeah, that's nice, C.J., but did you finish mopping the floors?'" Riley said."When we got the news ... it was just crushing. We're all having a hard time here."Other co-workers said Robinson also helped support others in his family financially.He had spent some time in Louisiana with his mother this summer before returning to Texas, they said.Investigation continuesPolice continued to investigate the crash and shooting Thursday.Police said Harper was involved in a crash near Collins and Washington Drive, then continued north on Collins, driving erratically and speeding. Other drivers followed to get a license plate number, police said."He left the area where he was involved in the first crash and people just followed him until he crashed the second time," Richard said.As he approached Brown Boulevard -- witnesses said the Tahoe was going at least 100 mph -- he crashed into a Dodge pickup, killing the driver.The victim was identified Thursday as Najee Nasir, 42, who lived in an apartment complex less than a half-mile away.Richard said Nasir had no family in the area."He has a friend here who has been working with officers and victims assistance to help contact the family," she said.Billy Ray Vaughn was one of the witnesses who rushed to the Tahoe to help those inside."I went to the SUV to help the kids," he said shortly after the crash. He said he approached the passenger side and saw that "the driver was ranting and raving, half-laughing. I saw him reach up and fire out the driver's window."A handgun was recovered at the scene, police said.Harper lived at the Copperstone Apartments in Arlington, about two miles from the crash site. On Thursday, a woman at his apartment confirmed that she was his wife but declined to comment further. Other people going into the apartment also declined to comment.A neighbor of Harper's, Greg Lawrence, said Harper and his wife seemed to trade off watching the kids. She worked almost every day, he said."I saw him coming and going from the apartment," Lawrence said.He said that on many Saturdays, Harper and his wife had big arguments about raising their kids."It was like someone hitting the walls with a lot of cursing," Lawrence said. He said he never saw police officers at the apartment.Harper's toddlers were taken to Cook Children's Medical Center in Fort Worth with non-life-threatening injuries Wednesday.'A bad, bad day'On Thursday, little evidence of the crash and shooting remained at the intersection. There were no impromptu flower memorials for Robinson or Nasir, and only a short piece of yellow caution tape fluttered from a traffic sign.But those who witnessed the wreck remember.At the nearby Valero gas station, Zahra Dhubow was on duty when the typical afternoon descended into mayhem."It happened around 1:40 or 1:50 p.m.," she said Thursday morning. "I was right here at the counter. I heard the noise. We all looked up and I was like, 'Oh, a bad accident.'"She described one "big bump" followed by others, then confusion as people tried to figure out what had happened."Everyone in the store and at the gas pumps ran over there," she said. "I was in shock. I thought no one could have survived."Then, Dhubow said, she heard a gunshot, and people began running back to the store."We locked the door and I called the police and we shut down," she said. "When I saw the people running back over here, I told myself it was a bad, bad day."She left the store at 5 p.m., and it remained closed until about 8, she said."I've never seen anything like that in my life," Dhubow said. "I wish I could have helped someone, but I couldn't."