IGUALA, Mexico (AP) -- On the day 43 students disappeared in this southern Mexican town, the mayor's wife was finishing up a speech to local dignitaries on family social services while townspeople waited for a celebratory dance afterward.
Suddenly shots rang out a dozen blocks away and people fled in a panic. Some think the incidents were related, though federal officials said late Tuesday they still have no explanation for violence Sept. 26 that killed six, wounded at least 25 and left so many missing.
Tough-looking civilians had been guarding the mayor's wife, Maria de los Angeles Pineda Villa, a woman with alleged family ties to organized crime. A police force that state and federal officials accuse of being infiltrated by drug gangs patrolled the streets.
Into this combustible mix came the students from a radical rural teacher's college that had defied drug cartel extortion in the past. Well-known for blocking highways and other protests, they arrived with plans to solicit donations from passers-by.
They were ending their fund-raising and meeting up to return home about the same time Pineda was finishing her speech. State officials say local police went on the attack, shooting at the buses students had hijacked for their return, as well as innocent bystanders in other vehicles.
Javier Monroy, an activist in Chilpancingo for the families of the disappeared, said the brutality of the attack "made no sense," but could have been caused by the local cartel, Guerreros Unidos, who thought the students were going to disrupt Pineda's speech.
Attorney General Jesus Murillo Karam declined late Tuesday to speculate on any link between the speech and the violence.
"I am not going to single out any hypothesis until I have it confirmed which is the correct one," he said.
Iguala Mayor Jose Luis Abarca is now a fugitive, and state officials have arrested 22 city officers. His wife's whereabouts are unknown. The possible massacre has focused attention on the extent to which local police forces such as Iguala's are permeated by organized crime.
Pineda, the mayor's wife, is from a family with known ties to the Beltran Leyva cartel. Prosecutors had identified her late brother, Alberto Pineda, as a main lieutenant in the cartel. He and another brother, Marco Pineda, both on former President Felipe Calderon's most-wanted list, were killed by rivals in 2009.
Another brother, Salomon Pineda, was released from prison last year and is believed to be running the Guerreros Unidos cartel in Iguala, an offshoot of the Beltran Leyva group, according to local media.
"Everyone knew about their presumed connections to organized crime," Alejandro Encinas, a senator from the mayor's Democratic Revolution Party, or PRD, told The Associated Press. "Nobody did anything, not the federal government, not the state government, not the party leadership."
Murillo Karam said there was no hard evidence before. Despite the rumors, and family ties were not sufficient grounds for prosecution.
"We don't investigate on the basis of kinship but rather facts," he said.
President Enrique Pena Nieto ordered a special federal police force to take over Iguala as his top security officials rushed to contain a smear on the image of stability and falling crime rates that they've projected to the outside world.
The chief prosecutor for Guerrero state, Inaky Blanco, said suspects have testified that as many as 30 members of the local police force were members of the Guerreros Unidos drug gang.
Blanco said the imprisoned municipal police deny killing anyone, but had bloodstains in the back of their pickup trucks. One policeman admitted handing over at least 10 detained students to "people he didn't know," Blanco added.
Security camera footage showed non-uniformed men forcing people into the back of a pickup truck, as others ran to escape.
One of them, Julio Cesar Mondragon, ignored his colleague's entreaties to take refuge in the home of a local resident and kept running, said Vidufo Rosales, a lawyer for the families of the missing students.
He was later found dead on the side of the road, the skin stripped from his skull.