Eyewitnesses have described the "pandemonium" of the Munich attack with people "screaming, shouting and running everywhere".
Nine people were killed, and 16 injured.
Jerome Burns, a holidaymaker from Northern Ireland, was at the city's central train station with his wife at the time of the shooting.
He told the BBC: "Suddenly we just became aware of an absolute pandemonium on the main station concourse - people just running absolutely everywhere.
"There was panic in their faces - we did not know what to do but immediately one of the security guards came into the office we were in, he closed the door.
"We were all ushered into the back of the office initially and then through a back door and down some back stairs into the basement of the station right down into the actual bowels of the station.
"We obviously were aware that something appeared to be going on because we knew about the attack in the shopping centre.
"There were very few people there that spoke English - there was one gentleman there that was keeping us aware of the situation.
"At that time it was thought there were three attackers and that one of them was in the underground system and was on his way to the station we were in.
"And it seems that is what gave rise to the initial panic."
Barman Sam Pound, who works in Kilians Irish Bar in Munich, spoke to the BBC shortly after the news of the attack broke.
He was in the middle of an interview describing the atmosphere in the city when his colleague began shouting at punters and staff to move to safety.
"Something is going on right now," Mr Pound said, who later confirmed to the channel that they were all safe.
Dominik Faust, who lives in Munich, said he was in the centre of the city in another shopping centre at the time of the attack.
He told the BBC: "They were not sure if there was another assassin in downtown Munich and all of a sudden there were people screaming and shouting and running."
Taking shelter in a store, he said security staff closed the doors and asked them to go up to the fifth floor to the offices of the employees.
"They asked us to stay calm and gave us something to drink," he said.
Mr Faust said police told the security staff they should keep all 150 people inside until they give the all clear sign as to when they could leave.
"We stayed there for about four hours until about 10pm and there was still no all-clear sign," he added.
Mr Faust said everyone kept informed as to what was happening through their phones and television, and from updates issued by the police, who he said were "brilliant".
"We were informed not to go to public places and the traffic was shut down - so we had just two choices, either to stay or go by foot or if someone had a car - to leave the city by car," he added.
One woman who wished to only be known as Lauretta told CNN she was in the McDonald's restaurant at the time of the attack and saw many casualties that were children.
She said: "I hear like an alarm and boom, boom, boom ... and he's still killing the children. The children were sitting to eat. They can't run."
Lauretta also revealed that she heard the gunman should "Allahu Akbar" Arabic for "God is great."
She added: "I know this because I'm Muslim. I hear this and I only cry."
Gunman is named locally
German Chancellor Angela Merkel is to chair a meeting of her government's security cabinet after the mass-shooting.
Police say they believe the gunman, who opened fire at a crowded shopping centre and fast-food restaurant in the city, is an 18-year-old German-Iranian who was not known to them. He has been named in reports as Ali Sonboly.
On Saturday officers remained at the scene collecting evidence. Police spokesman, Peter Beck, said they will "examine everything" as part of their investigation and "don't yet know what triggered the crime".
It is understood police raided a home in the the city's Marxvorstadt district, around 1.2 miles from the scene, and are believed to be interviewing the gunman's father. Mr Beck declined to confirm these reports, citing "ongoing police operations".
A neighbour on Dachauer Strasse that was searched by police on Saturday morning described the alleged gunman as "very quiet".
Wishing to only give his first name, Stephan, an owner of a coffee shop, said: "He only ever said 'hi'. His whole body language was of somebody who was very shy."
He added: "He never came into the cafe - he was just a neighbour and took out the trash but never talked."
Police said the victims killed in the massacre included teenagers, with children among the 16 people injured.
Investigators suspect the youth, who is thought to have lived in the south German city for more than two years, acted alone before killing himself.
Any motive behind the attack currently remains "totally unclear" and investigations will be "running on all cylinders", Munich police chief Hubertus Andrae said.
Speaking at a press conference in the early hours of Saturday morning, he said the attack "makes us speechless and our thoughts go out in particular to the victims".
Free food 'game'
A reporter at the press conference asked if a "game" posted on Facebook offering free food at the McDonald's at 4pm on Friday was an attempt to encourage people to congregate at the scene before the attack.
Mr Andrae said the game was "one part of the comprehensive investigation we are conducting".
The killings come after a 17-year-old Afghan asylum seeker launched an axe and knife attack on passengers on a train in Wuerzburg, southern Germany on Monday.
Islamic State claimed responsibility for the attack in which five people were injured. The teenage axeman, Riaz Khan Ahmadzai, was shot dead by police.