The unnamed officer, who is now in stable condition, joined the British Transport Police less than two years ago, Chief Constable Paul Crowther said in a statement.
“Having visited the officer in hospital shortly after he was admitted for treatment, I was able to hear his account of what happened last night," Crowther said, “Although he is seriously unwell, he was able to recount how he faced the attackers armed only with his baton, outside London Bridge station."
“The bravery he showed was outstanding and makes me extremely proud," Crowther said. "He showed enormous courage in the face of danger, as did many others who were at the scene and rushed to help."
Officials said assailants Saturday night used a vehicle to plow into pedestrians on London Bridge and then drove to Borough Market where people were attacked with knives. Three suspects were shot and killed in the wake of the carnage and all were wearing fake suicide belts, police said. It was eight minutes from the moment police were notified about the attack to when the three men were killed, police said.
Seven people were killed in what U.K. Prime Minister Theresa May called a "brutal terrorist attack."
Thirty-six people remain in hospitals Sunday, including 21 people in critical condition, police said.
Besides the injured British Transport Police officer, an off-duty Metropolitan Officer was also among the injured, the Metropolitan police said.
Crowther added, "Our thoughts are with all of those who died or were injured, and their loved ones as they try to come to terms with what happened.”
London Metropolitan Police said Sunday that a dozen arrests had been made in connection with the attack.
London Metropolitan Commissioner Cressida Dick said Sunday that police believe they had killed all of the attackers and that they "believed" that the incident was under control. Still a large police cordon remained in place in the area, south of the Thames, on Sunday.