The attackers who killed eight people on London Bridge last week had prepared a stash of Molotov cocktails and tried to rent a much larger truck to mow down pedestrians, British police said on June 10.
In a sign that the carnage could have been "even worse," police said they found 13 bottles filled with flammable liquid with rags wrapped around them in the white van rented by the attackers, along with two blowtorches.
The three assailants struck pedestrians with the van and then went on a stabbing spree in the popular nightlife district on June 3 before they were shot dead by police.
Police said attacker Khuram Shazad Butt tried to rent a 7.5-ton lorry hours before carrying out the attack, but was turned down because his payment failed.
Had he succeeded, the attack would have been "even worse," Counter-Terrorism Command chief Dean Haydon said, adding "were they then planning to come back to the van and ignite the Molotov cocktails and that was a secondary attack? We don't know -- I can only surmise."
Although the Islamic State extremist group claimed responsibility for the assault, Haydon said there's no proof the attackers were directed from abroad.