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 repeatedly in the chest.
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 assisting Mr Belanger in a restaurant courtyard next to and below the south end of 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.
She said she felt “a lot of pressure”, adding: “I was the only officer down there for a little while which felt like forever.”
Other police officers 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 moving him to an ambulance parked at a rendezvous point, the court heard.
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.