The NEC Arena is to review its security arrangements after two stewards were shot during a concert by US rapper Kanye West.
A 45-year-old security guard - who was shot at least three times in his neck, lower stomach and foot - remained in a critical condition in Heartlands Hospital last night after two operations.
His colleague, whose details are unknown, was released from hospital on Tuesday night following treatment for a graze.
Deborah Smith, communications director, NEC Group, said the level of security in place on Tuesday night had been based upon a detailed risk assessment.
"For this event we had in place standard bag searches and searches of bulky clothing," she said.
"However it's important to note that the individuals concerned did not gain entry as they did not have tickets."
However, police questioned how the gunman was able to take a gun into the venue foyer before being ejected for not having a ticket.
West, one of hip-hop's biggest stars, last night issued a statement saying: "My thoughts and prayers are with the two stewards who were injured last night."
The rapper is not known for employing violent imagery in his lyrics like so-called "gangsta rappers".
However, infamous rap mogul Marion "Suge" Knight was shot in the leg at one of West's parties last year.
Ms Smith added: "This is the first incident of this kind to have taken place at our venues.
"There will be a full internal debrief because no matter how good our procedures, there are always opportunities to learn lessons. We are very confident and proud of our staff and their responses and for now we are concentrating on getting operations back to normal and helping the police with their investigation."
Detective Chief Inspector Kenny Bell, from West Midlands Police, said the victims were shot between four and eight times outside the front entrance. My understanding is that this is not a gang-related shooting. What happened here was an unprovoked, brutal and cowardly attack," he said.
"This involved two members of the community working at the NEC whose aim of their job was to create a pleasant environment and make sure it is safe.
"There was a person in the building that should not have been there and they took professional action to remove them and in doing so were shot."
Appealing to the gunman himself, Det Chief Insp Bell said: "If there is one brave thing you can do, it would be to come and give yourself up."
The prime suspect is described as a black man aged between 18 and 22, 5ft 10ins and of slim build. He had a thin moustache and plaits in his hair down to the middle of his neck.
A 21-year-old man and a 20-year-old woman from Oldbury, Sandwell, were arrested close to the venue shortly after the incident, although Det Chief Insp Bell said the arrests were not significant.
The concert was underway at the time of the shootings with about 10,000 people inside and was not halted following the shootings.
West was performing the last night of his five-date Touch The Sky tour in the UK. n A concert by American singer-songwriter Jack Johnson went ahead at the NEC Arena as planned last night.
The level of searches was increased but the venue said this was purely as a precaution and described Tuesday night's shooting as "an isolated incident involving individuals who were not concertgoers".