Osasuna, needing a win to have any chance of retaining their La Liga status, moved ahead in the 12th minute of their game in Pamplona through Oriol Riera.
However, trouble followed in the ensuing goal celebrations.
The home supporters behind Betis' goal proceeded to react with understandable elation, but a section of a protective barrier keeping fans in the stand collapsed.
Numerous supporters spilled over the edge and on to the area of the pitch behind the goal and advertising hoardings, although the extent of any injuries sustained is not immediately clear.
Security officials and medical staff quickly attended the scene and, after the injured were taken off the field - with the help of Betis midfielder Alfred N'Diaye – the rest of the barrier was momentarily removed.
Play then continued after a break of more than half an hour.
