MONTERREY, Mexico (CNN) - Authorities are investigating what caused clashes that left at least 44 dead in a northern Mexico prison - and whether any inmates escaped.

A fierce rivalry between drug cartels likely fueled the fighting Sunday inside a prison in Apodaca, Nuevo Leon, state security spokesman Jorge Domene told reporters.

Prisoners could have used the riot to engineer a breakout, Domene said. He did not say whether inmates had escaped from the overcrowded prison or how prisoners inside acquired the clubs, stones and sharp objects they used in the fighting.

Guards may have been complicit, he said, and authorities have detained them - along with the prison's director - for questioning.