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.
Artist:
In Mulago Hospital, Proscovia was having a private room fitted with everything at the expense of Bebe Cool who had solicited for funds from various shows in support of the poor girl. Bebe Cool was grateful for the support that was extended to him after he had failed to walk, so he retaliated in a similar way.
