Assailants in an SUV hurled two grenades at a police station in the Pacific resort town of Zihuatanejo on Saturday, wounding one officer and four civilians.
Police and soldiers stepped up patrols and set up extra checkpoints after the attack in the popular beach town, according to the Guerrero Public Security Secretariat.
Three taxi drivers, a woman and a policeman were hurt.
The attack came a day after soldiers in Zihuatanejo arrested nine people in an organized crime sting - including the son of the former mayor of nearby Petatlán.
Officials in Zihuatanejo told the Spanish news agency Efe that they were investigating the possibility that Saturday's attack was an act of retribution for the arrests.
Grenade attacks have become a fixture in the nation's brutal cartel-related violence. Last week, five civilians and an officer were wounded in a grenade assault on a police patrol in western Michoacán.
On Wednesday, police reported finding the bound and bullet-ridden bodies of two men in a car in Zihuatanejo.
Zihuatanejo has suffered mounting violence in recent years as the area has become a key smuggling corridor for South American cocaine.
Now for a few details this story doesn't tell:
- You know the track I mentioned last week? The one where we've been going running? It's across the street from the police station and Ibis was there when the grenades exploded. He figures he was about 150 meters away and said he's never heard anything so loud.
We didn't find out until Saturday afternoon that it was a grenade attack; until that point a lot of people in town assumed it was a gas tank that exploded (something that's frighteningly common here).
- Among the nine people arrested on Friday was the son of the former mayor of Petatlan. I've mentioned Petatlan here before - it's the town that has had the ongoing violence between two drug families and the place we've stopped visiting because it's so dangerous.
Well some media outlets were reporting that the former mayor was among those arrested, so Saturday afternoon he held a press conference in Zihua to tell everyone that he's not involved with drugs. He went on to say that the business next door to his house is the one who's dealing drugs, and he questioned why the police didn't search that building.
Four hours later he was gunned down in the street. "Riddled with bullets" is how the newspaper described it.
Last night I found out that the former mayor was also Ibis' boss's godfather.
- Finally, the "western Michoacan" town that's mentioned in the article is Lazaro Cardenas, where my in-laws live and where we lived our first several months in Mexico.
This is all a little too close for comfort.