-- Another arrest was made early Saturday morning in connection with the London Bridge terror attack, just hours after police released additional details about the investigation, including a photo of a knife used by the attackers. On Sunday, police also released photos of the fake explosive belts worn by the terrorists.
"He was arrested on suspicion of being concerned in the commission, preparation or instigation of acts of terrorism under Section 41 of the Terrorism Act 2000," police said in a statement. "He has been taken into custody at a police station in Berkshire and is detained under the Terrorism Act."
He is the 19th person arrested in connection with the attack, but twelve of the individuals were released last week without charge.
Police released an image late Saturday night of one of "the distinctive pink knives used during the London Bridge terrorist attack."
The statement further explains, "The attackers had wound duct tape around the handles and in Butt's case, a leather strap had been attached to the handle and was hung around his wrist. It is this knife that police have released images of today."
Commander Dean Haydon, head of the Met's Counter Terrorism Command, said, "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. Where have they come from? Where might the attackers have bought them from? If you know anything about these particular types of knives, please let us know -- it could prove a crucial lead in our investigation."
On Sunday morning, police released images of the fake explosive belts worn by the three attackers.
All three men wore the leather belts. Each had three disposable water bottles covered in masking tape attached to the belt. The belts were still attached to the men when they were fatally shot.
Haydon said in a statement, "I have not seen this tactic in the UK before where terrorists create maximum fear by strapping fake explosives to themselves. Anyone who saw them on the night would have thought they were genuine. It is hard to speculate what the motive was for wearing the belts. It could be that they had plans to take the attack in to a siege situation or it might be that they saw it as protection from being shot themselves."
Police released additional details from its investigation, most notably, that Butt tried online to rent a larger, 7.5 ton truck that could have killed more people, but his payment was declined.
After Butt's payment was declined, the trio of terrorists rented the smaller van that they used to plow into crowds before jumping out of the vehicle and going on a stabbing rampage that left eight people dead and almost 50 injured.
Police also revealed that the attackers had stored in the van petrol bombs -- several wine bottles filled with flammable liquid and rags wrapped around them -- but police fatally shot the trio before they could return to the van and kill even more people.
Police also said they found a copy of the Quran opened at a page "describing martyrdom" at one of the attackers' houses.