Police personnel patrolling Manchester Arena were absent from patrol for more than two hours and suicide bomber Salman Abedi was missed by just seconds by a second patrol, the public inquiry into the terror attack heard.
Just four British Transport Police (BTP) operatives were present on the night of the attack, one Pc and three PCSOs, patrolling in pairs, the hearing in Manchester was told.
Pc Jessica Bullough and a PCSO Renshaw took a break around 7.30pm, leaving Manchester Arena to buy food, as the Ariana Grande concert began on May 22 2017.
They returned 45 minutes later and resumed patrolling two hours and 10 minutes after they first departed to buy food, the inquiry heard.
Two more PCSOs, Morrey and Brown, took an hour's break from 9.15pm.
Between 9.15pm and 9.37pm, it appears no BTP officer was patrolling the railway station when Abedi took up his position at 9.33pm in the City Room, the foyer of the venue.
The inquiry has heard of "missed opportunities" in the hours before Abedi, surrounded by a throng of elated youngsters leaving the show, detonated his explosive at 10.31pm sending thousands of nuts and bolts shredding everything in their path.
Hundreds were injured and 22 people were killed.
Earlier the two PCSOs had conducted a routine check on toilets at Victoria Station, the site of the Arena venue, at 8.49pm, less than a minute after Abedi left there.
Abedi, 22, dressed in black and bent over by the weight of the shrapnel packing his home-made bomb in a large rucksack on his back, later made his way to the foyer of the Arena.
Both police and Showsec security workers later received reports of suspicions from members of the public about Abedi, the inquiry was told.
Sir John Saunders, a retired High Court judge, is leading the probe, expected to run into next year, examining events before, during and after the attack, including the radicalisation of Manchester-born Abedi.
His brother, Hashem Abedi, now 23, was in August jailed for life with a minimum 55 years before parole, for his part in the deadly bomb plot.
The hearing was adjourned until next Monday.