Police were last night quizzing a man on suspicion of causing death by dangerous driving after a woman, her unborn baby and her nine-year-old son were killed on a pelican crossing.
The 28-year-old woman, who was six months pregnant, is believed to have been carried up to 50 metres under the car.
The woman, named by locals as Sarah-Jayne Hunt, was pronounced dead at scene in Hay Mills, while the nine-year-old boy, Kieran, lost his fight for life in hospital.
A second boy - the woman's youngest son - was with them and was also struck by the car. He was last night in Birmingham Children's Hospital being treated for severe shock.
The accident happened on the Coventry Road at its junction with Ada Road near the Bill and Bull pub at about 6.15pm on Tuesday Witnesses frantically tried to give first aid to the victims. They claimed the car passed through red traffic lights before hitting the mother and children.
One woman said: "It was horrific. I raced over to them but it was obvious the woman was dead. I sat with the eldest boy and willed him to stay alive. He was unconscious."
She said the children's father, Scott Hunt, had picked the boys up from school and then dropped them off with their mother. The couple were understood to have been divorced.
"They were crossing the road when the car drove straight through a nearby red light and ploughed into them."
Vikas Ahmed Ditta, aged 16, from Small Heath, said he was on his way to work at the Big Eat takeaway in Coventry when he witnessed the aftermath of the accident.
"Paramedics were giving mouth-to-mouth and pushing the chest of the little boy," he said. "He looked lifeless. It was just awful."
Cards and flowers were being left at the scene last night by shocked friends and relatives. One tribute read: "Our hearts are with you both, you will be greatly missed by all of us.
"No words can describe the pain and hurting. Love you both, good night and God bless. Lots of love from Toni, Simon, Ellie and families."
A spokesman for West Midlands police said a 19-year-old local man had been arrested and was being questioned in custody. "Reports that the woman and her two sons were using a pelican crossing at the time of the collision form a significant part of our inquiry and we want to hear from anyone who can help us establish the facts surrounding this tragic incident."
A crash near Birmingham city centre claimed the life of another boy and a woman yesterday.
The four-car pile-up happened in Viceroy Close at its junction with the Bristol Road at about 8.30am.
Three casualties, including the two who died, had to be cut free by firefighters from the wreckage. The third victim suffered serious injuries and the other two casualties received minor injuries.
Five ambulances and the C ounty Air Ambulance arrived at the scene of the road accident to take the casualties to Selly Oak Hospital.
Police had to close a number of roads off Bristol Road, Lee Bank Middleway and Belgrave Middleway while dealing with the incident and undertaking an accident reconstruction.
The crash brought chaos to the area, with some roads remaining sealed off until 1.30pm. Anyone with any information is asked to contact police at Belgrave Middleway on 0845 113 5000.