The man was refused entry as he appeared drunk. He then produced a gun and opened fire at the casino’s foyer injuring two female guests and a security guard, according to the police.

“One was hit in the arm, one in the leg and one in the stomach, according to the information we have received,” said police spokesman Janne Hedlund.

All three were taken to St. Göran’s hospital in central Stockholm. The hospital confirmed that it did not consider the injuries to the female guests as life-threatening.

The guard, who was hit in the stomach was then taken to Karolinska University Hospital and the state of his injuries were unknown on Thursday morning.

Police launched a massive operation on Christmas Day to search for the unidentified gunman who may have fled the scene in a taxi.

“We have sixteen or seventeen police units out searching for the perpetrator,” said spokesman Magnus Axelsson.

Raad Malki stood at the first row of slot machines just metres from where the gunman opened fire. He did not however get a look at the perpetrator, who remained on the loose at midday on Thursday.

According to the doorman who alerted the police, a man opened fire with a handgun after he was denied entry to the casino.

Following an examination of security footage, police described the perpetrator as male, 1.80 metres (6 feet) tall, with short cropped fair hair. He was wearing a black jacket with a logo on the upper arm, blue jeans, black shoes and white socks.

Malki told how when he turned around he saw a woman fall to the floor and a guard stumble. The woman was bleeding from her arm and Malki noticed a large wound. He then heard three shots in quick succession.

“Then chaos broke out,” Malki said to news agency TT’s reporters outside the Casino Cosmopol on Kungsgatan in central Stockholm where around 300 guests had passed through the casino on Christmas Eve before the gunman struck.

“People threw themselves under tables and a guard screamed, I was shocked and scared but I didn’t realize at first what had happened,” he said to TT.

Taxi driver Adam Khalil was also a witness to the attack.

“Suddenly I heard the shot. Several people threw themselves under tables, some ran up to the second floor, while others escaped out the back – myself among them,” he told TT.

In the mayhem Khalil lost contact with his brother.

“I was worried,” he said.

Khalil was still waiting outside the casino at 2am in order to get back in and reclaim his jacket which he had left in the coat check.

Andreas Jansson at Svenska Spel, the state-owned operator of the casino, described the events as “tragic”.

“The most important thing for us now is to take care of our staff and our guests. We have a considerable security operation in place, but we will naturally have a review and see how we can tighten it,” he said.

“Although it is naturally very difficult to protect yourselves against something like this,” he concluded.

The remaining casino guests were allowed to leave the premises by the back door around a hour after the shooting.

“The police did not want to release anyone as they wanted to inspect the entrance to the casino where the shooting occurred,” said casino guest Antonio Faniadis.

Police were combing the vicinity of the casino on Christmas Day looking for the weapon in litter bins and other potential hiding-places.

The police on Thursday deployed helicopters in their search for the perpetrator. As the man was caught on the casino’s security cameras police are confident that it is just a question of time before he is in custody.

Police have cordoned of the area around the casino, which is located on Kungsgatan in the city centre.