Drones carrying large amounts of drugs and mobile phones have been intercepted by police as they were being flown near a north London jail.
One device crashed after it was tracked flying over HMP Pentonville on 14 August, while another drone was seized mid-flight later the same day.
On 13 August, a man was spotted by officers acting suspiciously near the prison. He fled but dropped two bags of class B drugs and phones.
No arrests have been made.
Det Ch Insp Steve Heatley said the drones "carried a substantial amount of class B drugs, legal highs and a large quantity of mobile phones".
"We are able to intercept them thanks to the vigilance of officers and the public," he said.
The devices were recovered as part of Operation Airborne, which involved officers investigating attempts to smuggle contraband into the all-male prison over the weekend of 12-14 August.
Two other drones got away during the operation, police said.
Earlier this year it was revealed that drones were increasingly being used to smuggle items into prisons in England and Wales.
Figures showed there were 33 incidents involving devices in 2015, compared to two in 2014 and none in 2013.
Drugs, phones, mobile chargers and USB cards were among the items discovered.
The use of drones is a particular problem at older jails like HMP Pentonville, according to officers.
"They've worked out they can drop drones into the prison yard... because the fences aren't as high and they're built near houses", Det Supt Stuart Ryan said.
In April, a drone carrying contraband was captured on CCTV being flown into Wandsworth Prison, a jail built in the 1850s.
Andy Darken of the Prison Officers' Association said the prison service "doesn't really have the resources, means or indeed the know how yet of how to deal with the problem".
In February the Met said it was "looking at the work of the Dutch police use of eagles" as a method to intercept devices.
The Ministry of Justice said it was "doing more" to tackle the issue.