Mexican security forces killed two people believed to be involved in a string of attacks on electrical installations at the weekend and captured three more, the government said on Monday.
An unspecified number of substations and gas stations were attacked and damaged early on Sunday in the troubled western state of Michoacan in an attack that temporarily knocked out power for hundreds of thousands of people.
National security spokesman Eduardo Sanchez said authorities were still investigating the attacks but added that two men suspected of being involved had been killed in a firefight with soldiers, while three others had been captured.
"These men ... have been hospitalized as a result of injuries caused by the flipping over of the car they were trying to flee in," Sanchez said. It was not immediately clear when the killings and arrests took place.
He said that power had now been restored to all the affected regions. Local media said blackouts had plunged into darkness more than 400,000 people across the mountainous state of some 4.4 million.
Mexico stepped up security in the troubled western region in the wake of the attacks.
Energy Minister Pedro Joaquin Coldwell said security forces had increased their presence at facilities of the state-run electricity company the Federal Electricity Commission (CFE) and oil monopoly Pemex in Michoacan.
Parts of the state have fallen under the control of criminal gangs who are fighting among themselves and against authorities.
In a radio interview, Michoacan's interior minister, Jaime Mares, declined to say who may have been behind the attacks in the state, where clashes between the powerful Knights Templar drug cartel and rival gangs have sparked much violence.
Raul Benitez, a security expert at the National Autonomous University of Mexico (UNAM), said he believed the strikes had been carried out by the Knights Templar in retaliation for government efforts to crack down on the gang.
"It's a decision to carry out general terrorism," Benitez said. "And this will now lead to a very strong response by the government, backed by the population."
Petrol bombs were used in some of the attacks, which involved at least 19 CFE installations, local media said.
Mares said there were no deaths in the attacks, although local media reported that five suspected cartel henchmen were gunned down by vigilantes in the town of Aguililla near the city of Apatzingan, a stronghold of the Knights Templar.
Michoacan has been rocked by repeated explosions of civil unrest this year, and protesters have repeatedly blocked major streets and highways in the capital and other cities.
Adding to the violence, vigilante groups have sprung up in the region this year in reaction to what they say is lack of protection by state and federal police against the gangs.
President Enrique Pena Nieto in May sent a general to take over all police and military operations in the state.
Michoacan was where former President Felipe Calderon launched his military-led crackdown on drug cartels shortly after taking office at the end of 2006.
Though he succeeded in capturing or killing many drug lords, Calderon could not contain the violence between the gangs, which has since claimed around 80,000 lives.