A police officer said she waited for back-up for what “felt like forever” during the London Bridge attack.
PC Mia Kerr told an inquest she drew her baton to guard members of the public as they tried to save victim Sebastien Belanger after he was stabbed on 3 June 2017.
The court heard she repeatedly called the police control room to ask for help from paramedics, but none came.
Mr Belanger, 36, was one of eight people killed in the attack.
The chef, originally from Angers, western France, had been drinking at the Boro Bistro when he was stabbed in the stomach.
PC Kerr told the Old Bailey she had been a police officer for about a year on the night of the attacks.
She said she came across members of the public giving first aid to Mr Belanger at 22:12.
‘A lot of pressure’
He had collapsed in Green Dragon Court, below where the attackers’ van had crashed into railings on London Bridge.
After deciding that the group “looked like they knew what they were doing”, PC Kerr drew her baton in case the attackers returned to the area.
“I was the only officer down there for a little while which felt like forever,” she said.
“I’d only had about a year of service so it was a lot of pressure.”
Another police officer and a police medic arrived over the next few minutes, the court heard.
The court heard that no members of the London Ambulance Service came to the scene to help Mr Belanger, despite PC Kerr calling the Metropolitan Police control room to request paramedics.
The inquest previously heard that the area had been deemed too dangerous for paramedics to attend.
Two members of the public and the officers spent more than half an hour performing CPR on Mr Belanger before he was eventually moved up steps to a waiting ambulance at about 22:45, the court heard.
‘I just wanted some help’
BBC correspondent Richard Lister, at the inquest
PC Kerr was composed as she told the inquest about how she, another officer and two members of the public fought to revive Sebastien Belanger.
She talked of initially being the only police officer there.
“Time just stood still. I just wanted some help,” she said.
The Belanger family listened intently to their interpreter as PC Kerr described standing guard while Lisa Deacon and Craig Smith did what they could for Mr Belanger.
None of them knew whether the attackers would come back and PC Kerr, who only had a baton for protection said: “I was very aware that where I was standing, I was trying to cover three potential entrances and exits.”
Ambulance service incident response officer Nicholas Lesslar told the court he was unaware there were seriously injured casualties in the courtyard.
Questioning PC Kerr on behalf of the victim’s family, Gareth Patterson QC said: “If you had been told there were LAS [London Ambulance Service] resources available before then, up on the High Street, presumably you would have discussed getting Sebastien up to those ambulances as quickly as possible?”
PC Kerr said: “We would have discussed it, yes.”
Mr Belanger’s mother told the inquest on its opening day that she was “so proud” of him.
The other seven people killed in the attack were James McMullan, 32, Xavier Thomas, 45, Alexandre Pigeard, 26, Chrissy Archibald, 30, Ignacio Echeverria, 39, Sara Zelenak, 21, and Kirsty Boden, 28.
The inquest into their deaths continues.