MEXICO CITY, Mexico (AP) — Three people, including a minor, were being held Sunday in the slaying of a newly inaugurated mayor in a gang-troubled central Mexican city.

Morelos Gov Graco Ramirez ordered flags on state buildings flown at half-mast and called for three days of mourning following the murder of Temixco Mayor Gisela Mota.

He blamed organised crime for killing the 33-year-old Mota, a former federal congresswoman who had been sworn in as mayor less than a day before she was gunned down in her home Saturday morning.

Ramirez ordered security measures for all of the state’s mayors, though he gave no details on what that involved.

Ramon Castro, Roman Catholic bishop of Cuernavaca, celebrated mass at Mota’s home Sunday and later spoke critically of a state where some areas are in control of organised crime.

“One theory could be that it was a warning to the other mayors,” Castro said to reporters. “If you don’t cooperate with organised crime, look at what will happen to you. It’s to scare them.”

Following Mota’s killing, two suspects were killed in a clash with police and three others arrested. Officials said they include a 32-year-old woman, an 18-year-old man, and the minor.

They gave few other details, though state Attorney General Javier Perez Duron said they had been tied to other crimes. Temixco, with about 100,000 people, is a suburb of Cuernavaca, a city famed among tourists for its colonial centre, gardens and jacaranda-decked streets.

“The city of eternal spring” was long a favourite weekend getaway for people from nearby Mexico City. But drug and extortion gangs have plagued the area in recent years, driving away some tourists and residents.

The expressway — and drug routes — between Mexico City and the country’s murder capital of Acapulco cuts through Cuernavaca and Temixco. Neither the governor nor prosecutors indicated which criminal organisation might be involved.

Drugs, kidnappings and extortion in the area were once under the control of the Beltran Leyva cartel, but that group’s collapse a few years ago unleashed fierce competition among its progeny and rivals in Morelos and neighbouring Guerrero and Mexico states.

In December 2014, a state lawmaker who was a candidate for mayor of Temixco from the same party as Mota was kidnapped there.

Authorities rescued him the following day and blamed the Guerreros Unidos cartel which has been clashing with a group known as Los Rojos in Guerrero and Morelos.