Nabila Nanfuka, 22, of Neasden, north-west London, died in Lava and Ignite in St Peter's Street in the early hours.

One witness, James Adetula, 21, said a "stampede" had begun as people made for the exits when they were told that their buses were leaving.

The number of people in the club is unknown and is under investigation.

Supt Andy Cox, of Northamptonshire Police, said they were aware of large numbers of people at the 1,600-capacity venue.

Officers are also looking at whether the club's fire alarm was activated before the crush, he told a press conference.

Clubber James Adetula describes the scene
Ms Nanfuka was studying leisure and tourism at the University of Northampton.

Her family described her as "one in a million" and a "beautiful person".

Six people were treated for minor injuries and a number of people were treated at the scene, the hospital said.

The event, called DNA Presents Wickedest Wickedest, started at 21:00 BST on Tuesday and was due to go on until 04:00 BST on Wednesday. Emergency services were called to the scene at 03:37 BST.

Birunji Nakiwala, 22, said: "Coaches bussed students there from different universities.

"It was packed. A lot of people were trying to get in. Not everyone had a ticket but they were told they could buy them on the door, even though it was sold out. It was way over-capacity, I couldn't breathe.

Then there were so many people trying to get out at the same time. Everyone was panicking about missing the buses. Hundreds of people were rushing down the stairs.

"People were pushing behind. By the time we realised it was a dangerous situation, we couldn't get back. People were fainting. At the bottom of the stairs people were falling over."

Birunji, a law student at Essex University, was rescued by bouncers. She said: "I was dragged out — but they didn't get Nabila out in time.

"We were told she had a cardiac arrest. She was the most amazing, vibrant person."