Shooters have stormed a drug rehabilitation centre in main Mexico, killing 24 individuals.
A minimum of seven others were injured including three seriously in the attack on Wednesday, according to police.
It is the 2nd attack at a rehab facility in Irapuato, Guanajuato, within a month, and among the mostly deadly massacres this year.
The intention is unknown but gangs frequently target clinics where they think members of rival factions are concealing.
The most recent rehabilitation centre to be struck was not officially signed up, according to authorities.
The state has hundreds of informal treatment centres. The previous attack – at a close-by centre called Starting a New Life – eliminated 10 people.
Police told local media that, in the most recent ambush, several shooters leapt out of a truck and rushed into the building, where they forced those present to drop to the floor prior to shooting them.