Mexico's navy said Wednesday that its personnel had no idea they had killed the leader of the country's most-feared drug cartel until after his body was stolen from a funeral home in this border town.

The death of Zetas cartel leader Heriberto Lazcano, alias "El Lazca," in a gunfight with marines Sunday left a wake of fear in the small mining and farming towns that dot the northern plains of Coahuila state.

Residents of Progreso said they heard a series of three loud explosions Sunday, apparently from the grenades that Lazcano reportedly fired at marines who were pursuing him.

But most people refused to talk or said they weren't at the baseball field near where Lazcano died of gunshot wounds. Those that acknowledged hearing the explosions said they ran into their homes and stayed inside.

It was unclear why Lazcano was at the baseball field. A game between Progreso and a neighboring town was in progress, but the area around the field is also one of only two spots in town with reliable cellphone service.

It is clear why this area was attractive for the Zetas, the brutal cartel that Lazcano helped found after deserting from Mexico's army. Progreso has had no municipal police force since January, because local officers refused to submit to the background checks and vetting that are now required of police.

"We have issued public invitations to see if people want to join the police, but nobody shows up," state police officer Manuel Hernandez Mireles said. A few state officers now provide the only security in the town.

In the neighboring town of Presa San Martin, an elderly shopkeeper who didn't want to give her name for fear of reprisals said drug cartel gunmen have been hanging around the town for three or four years, apparently drawn by the area's isolation and the absence of police.

"This town is abandoned, in all the senses of the word. That's why those people come here," the shopkeeper said.

"We see the trucks speeding by. We are afraid to walk in the street," she said.

The navy says Lazcano was killed after marines tried to search a group of suspicious men outside a baseball stadium, after receiving a tip there were armed men in the area. The men fired on the marines and a firefight raged, it says.

Rear Adm. Jose Luis Vergara said in radio and television interviews Wednesday that Lazcano's body was left at a funeral home along with the body of an accomplice after the gunfight because marines believed he was just a common criminal and didn't suspect they had just taken down the leader of the Zetas cartel.

"For us it was two more criminals. We had no indication that it was 'Lazca,'" the admiral told MVS Radio.

Vergara said authorities only realized they had killed a significant figure when armed men stole the body from the funeral home. Checks of fingerprints taken from the body confirmed the dead man was Lazcano.

The spokesman also revealed for the first time that a third suspect was present during the gunbattle and escaped.

He said it was increasingly common for drug-cartel leaders to travel in small groups instead of heavily armed convoys, in order to attract less attention.

The fallen capo was an army special forces deserter whose brutality and paramilitary tactics transformed a small group of drug cartel enforcers into one of the world's most feared international criminal organizations.

Analysts say his death could set off a power struggle inside the Zetas as its relatively autonomous local cells decide whether to align with its remaining boss, Miguel Angel Trevino Morales, a man considered even more ruthless and brutal than Lazcano.