At least 43 people were killed on Friday in Mexico's Michoacan state following a clash between an armed group and federal police, authorities said.
Sources from the government's security cabinet told Xinhua the armed group launched the attack against agents in the township of Tanhuato.
A preliminary police report leaked to EFE news agency put the death toll at 43, but said that all of the fatalities were gunmen.
Michoacan Governor Salvador Jara said he would not comment until his administration has a clearer idea of what happened, though he mentioned that the shootout apparently began when federal officers tried to pull over a suspicious vehicle.
The morning clash took place along a stretch of highway near the community of Tinaja de Vargas, on the border with neighbouring Jalisco state, in the Vista Hermosa region. Both Michoacan and Jalisco have been rocked by drug cartel violence lately.
Members of the security cabinet, headed by the interior ministry, travelled to the site to assess the situation, the same sources said. A more complete report is expected later in the day.
Media reports said the attack was organised by Jalisco's New Generation cartel.
