Brooks, 37, Lawrence’s best friend, broke down while giving evidence, but chose to continue despite he fact that his father passed away in the night.
He told the court that Lawrence has been confused and didn’t seem to realise how seriously he was wounded.
“We were running and he kept asking me to tell him what was wrong because he can’t run properly,” Brooks said.
“Blood was streaming out around his neck and through his jacket.”
Duwayne Brooks arrives to give evidence at the Stephen Lawrence trial
The attack took place in Eltham, South London, in 1993. Lawrence and Brooks, who had been friends since they were 11, were set upon by a group of white youths, who apparently shouted “What, what n***er?” before setting upon the two teenagers.
Brooks said that when Lawrence got up and started to run, he initially believed that his friend would be OK. However the gang chased them with weapons believed to be a metal bar and a knife.
“When I looked back I saw, at that moment in time, I don’t know if you could call him the leader, but the guy who had the weapon, ran straight into him and, wham, just like that,” Brooks said.
“It was something shiny.” Brooks indicated with his hands that the weapon had been about a foot long.
He continued: “When I was being chased he had like a metal bar in his hand, and when I ran back he hit Stephen with the bar. He was getting up and he hit him which made him go back down.”
After Lawrence collapsed in the street, Brooks tried to get help using a phone box but the geographical information inside was wrong.
He described how his friend slumped bleeding against a tree and died.
Gary Dobson, 36, and David Norris, 35, who are accused of murdering Stephen Lawrence, took notes as Brooks gave evidence to the jury.
Both men deny the charges.