A senior police officer who authorised the use of lethal force against a man who was later shot said he thought the first 999 call was malicious.
Chief Inspector David Guthrie of Northumbria Police told an inquest of the "fast-moving and dynamic" situation which led to James Carlo Wilson being shot by a police marksman.
The police received an anonymous call at 12.57am and by 1.35am Mr Wilson had been shot outside a house in Frenchman's Way in South Shields.
A jury at the inquest at Mansion House, Jesmond, heard Mr Wilson died in hospital on April 1, 2016, three days after he was shot.
Chf Insp Guthrie said he was on duty as joint force operations manager and tactical firearms commander in a room at Northumbria Police's headquarters when the incident was passed to him by control room staff in South Shields, who had taken an anonymous 999 call.
The call said James Wilson, who was 24, had a 9mm gun and was outside a house in Frenchman's Way, South Shields.
Chf Insp Guthrie told the inquest: "I had to decide on the appropriate response.
"I asked the control room to try to contact the caller again to get more information, but they were unable to do so.
"We had the number, but it was not a number known to us. The caller appeared drunk, and there was no other corroboration.
"No other member of the public had called about a man with a gun in Frenchman's Way, so my initial assessment was the call was malicious.
"However, a firearm had been mentioned, so no response was not an option."
Chf Insp Guthrie said he asked a unformed officer in South Shields to identify a rendezvous point for police resources.
The officer continued: "I was a Bank Holiday. There were two armed response vehicles on duty, they had to cover the whole force area from Sunderland to Berwick and across to Cumbria.
"One armed response vehicle was in Newcastle city centre, and the other was at the airport.
"I asked for both of them to travel to the scene, but without armed authority at that point ."
The inquest heard Chf Insp Guthrie changed his view of the situation after a traffic officer, PC Huntley, in an unmarked car drove along Frenchman's Way.
"He reported there was a man outside a house in Frenchman's Way, and he had something black in his hand," said Chf Insp Guthrie.
"He couldn't see if it was a gun, but it was some corroboration of the anonymous call.
"We had also been back in touch with the anonymous caller, and some threats had been made about shooting police.
"At 1.22am I briefed the firearms officers, and I instructed uniformed officers to form an outer cordon.
"The ideal situation being for the firearms officers to control the man with the gun, and for the uniformed officers to prevent members of the public from coming into contact with him.
"I was conscious that it's a residential area, and I couldn't prevent someone emerging from one of the houses.
"The safety of the public being my top priority."
The jury heard a recording of police officers telling Mr Wilson they were armed, and that he should put down the gun.
When he did not he was shot with a plastic bullet by one officer, then shot by another officer with a rifle.
The inquest is proceeding and is expected to last three weeks.