The murderous trio behind the London Bridge attack filled their van with petroleum bombs, used mysterious ceramic pink knives and originally planned to rent a 7.5-ton truck, suggesting that they intended more carnage before officers shot them dead, police said Friday.
Metropolitan Police in London appealed for information about the ceramic knives used in last weekend's attacks that killed eight people. The non-metallic nature of the knives suggests the killers may have been concerned about metal detectors.
"We've been working round the clock to understand what these men did in the lead-up to the attack but we need to know more about these unusual knives," said Commander Dean Haydon, head of the Metro Police Counter Terrorism Command.
"Where have they come from? Where might the attackers have bought them from?" Haydon said in a statement. "If you know anything about these particular types of knives, please let us know — it could prove a crucial lead in our investigation."
The kitchen knives, each measuring about 12 inches, are branded Ernesto, police said. The attackers had wound duct tape around the handles and, in the case of attacker Khuram Shazad Butt, a leather strap had been attached to the handle and was hung around his wrist.
An Internet search reveals that a German-language shopping site sells what appears to be the knives, or at least something that is extremely similar.
In a rare glimpse into the weeklong investigation, police released details on Saturday that showed Butt originally tried to rent a 7.5-ton truck. The intended truck was smaller but similar to the one used in the Nice attack last year that killed 86 people and injured hundreds in the resort town in the south of France.
After his payment was declined, Butt and his two accomplices rented a smaller van that they used to plow into crowds before they leapt from the vehicle and went on a stabbing rampage in an attack that left eight people dead and nearly 50 people injured. It was the third such deadly attack in Britain in three months.
Police also disclosed that multiple petrol bombs were discovered in the van, and a copy of the Quran opened at a page "describing martyrdom" was found at one of the attackers' houses.
Investigators believe three victims were killed on the bridge, including one man who was thrown into the Thames River, before the attackers left the vehicle and stabbed five people to death around London's busy Borough Market, Haydon said. Police believe Butt was driving the van.
"When I come back to Butt trying to get hold of a 7.5-ton lorry — the effect could have been even worse," Haydon said.
More than a dozen wine bottles filled with flammable liquid and rags wrapped around them in the shape of Molotov cocktails were found in the van. Two blow torches were also found.
Haydon said the men may have been planning even more bloodshed if they had survived their stabbing spree and made it back to the van.
Police also found a number of office chairs, gravel and a suitcase in the van.
Detectives believe the gravel may have been placed in the vehicle to make it heavier, or as part of a cover to justify hiring it, while the chairs may have been used to convince family and friends they were moving furniture.
Butt, a 27-year-old Pakistan-born British citizen, and his two accomplices, Rachid Redouane, 30, who claimed to be Moroccan-Libyan, and Youssef Zaghba, a 22-year-old Italian national of Moroccan descent, were shot dead by armed police eight minutes after the first emergency call.
The three attackers were wearing fake suicide belts consisting of plastic water bottles wrapped in grey duct tape.
Police raided Redouane's small residence on Tuesday and said he had been renting it since April. This was the safe house where the attack was planned, police said. In the residence, police found an English language copy of the Quran opened at a page describing martyrdom, pieces of cloth which appeared to match material wrapped around the petrol bombs and water bottles similar to those used in the fake suicide vests, police said. Luggage straps, plastic retractable craft knives and rolls of duct tape were also found.
Eighteen people have been arrested in connection with last week's attack. All but five have been released. Searches are continuing.
Contributing: The Associated Press