A bomb went off towards the end of an Ariana Grande concert in Manchester killing at least 19 and injuring 50, local police have confirmed. As fans were exiting the arena after the concert ended, a loud explosion was heard and the foyer was filled with smoke. It is being treated as a terrorist incident, said police.

Another update from a Guardian editor said that among those arriving at the Manchester Royal infirmary for urgent care were children.

“The lights come on and I was waiting to leave and there was a huge bang,” said 19-year-old Heidi Wood, who attended the concert with her boyfriend’s sister. “Everyone on the floor started running and screaming and I couldn’t process what was happening, so I started just following the crowd out.”

“When I got into the foyer there were so many screams and crying and a man was screaming his daughter’s name. I asked security what happened and they were saying, ‘Just leave for your own safety.’ When I got outside there were people vomiting in the street and screaming.”

“It was so traumatising. I can’t get it out of my head.”

Many were confused at first about what had occurred, as Grande’s concert finished with balloons falling from the arena’s rafters onto the crowd. Some assumed that the loud bangs were due to popping balloons. Amy Garvie, 19, was still inside the arena when the explosion sounded. “The explosion seemed to be in the foyer just outside our block, but it was in the foyer so didn’t see anything actually happen, just a lot of smoke when we got to the foyer,” Garvie said. “Two of my friends were elsewhere in the arena and we’re all from Scotland and just travelled here for the concert,” she said, adding, “We’re all safe back at our hotel now.”

While many got home safely, there are still reports of people missing or unaccounted for. Friends have begun posting images of the missing concert goers on Twitter, asking if anyone has seen them.

As emergency services continue to respond, those who made it out safely are offering their homes to stranded or scared fans via the hashtag #roomformanchester. “If any1 stuck in Manchester needs a safe place to stay / chill I am 10 minutes from the centre. Please DM if you need to #RoomForManchester,” read one tweet.

Ariana Grande’s publicist confirmed the singer was safe following the incident. Grande tweeted later in the evening that she was “broken” and “so so sorry” for what transpired.

Nicki Minaj, Lorde, Harry Styles and more have taken to Twitter to share their condolences with victims of the attack.

For updates on the incident, follow the Greater Manchester Police on Twitter, and call 0161 856 9400 if you are concerned about missing loved ones. If you have a room available you can tweet with the hashtag #RoomforManchester. Some attendees were taken to the local Holiday Inn, and parents or guardians are urged to dial this number 07896711298.