Updated at 4:30 a.m. ET Thursday
British authorities have made eight arrests in their investigation into Wednesday's attack in London, police said Thursday morning.
Mark Rowley, the national lead for counterterrorism policing, told reporters that there were four dead, including the attacker, and 29 people have been treated in hospitals. Seven people are in critical condition, he said.
Police had earlier said there were five dead including the attacker.