MATAMOROS, Mexico (AP) _ A ''wave of bloody violence'' grips this border city of 500,000 where 30 people, six of them gunned down in the streets, have been killed since the first of the year, a police official says.

State Police Cmdr. Ricardo Zolezzi Cavazos blamed the violence on the pressures of life in a big border city with many people looking for work.

Thirty people have died from gunshot wounds, stabbings or blows to the head in the past three months, Zolezzi Cavazos said.

More than 10 others died in accidents, most of them drownings in the Rio Grande during illegal crossings into Texas, he added.

However, the chief of the municipal police force estimates that the number of murder and drowning victims is closer to two dozen and disagrees with the state police official's statement about crime in Matamoros.

''It's not a wave of violence. A wave is when it's organized crime, or permanent, like guerrilla warfare,'' Javier George Portes, chief of the municipal police force, said Monday.

''There is no such thing as really and truly organized gangs'' in Matamoros, he said. Nonetheless, he admitted that the ''high index'' of murders is hurting the city's image.

Zolezzi Cavazos said the number of deaths so far this year exceeds all of the homicides in an average year; however, Portes said there are an average of 50 suspicious deaths a year.

The state official, who leads 30 investigators in this northeasternmost city along the Mexican-U.S. border, said he's asking for 100 reinforcements and more equipment and arms.

Although he blamed a lack of jobs for many of the killings, Zolezzi Cavazos said Monday that others are drug-related or occurred because people were fighting for land or ''for reasons of women.''

''There are a lot of reasons people want to kill each other - land problems, love problems. You know, Latins are pretty hot-tempered,'' said Fernando Domene, chief of internal affairs for the municipal police department.

Six of the victims died in the streets of this city, across the border from Brownsville, Texas, where unskilled workers earn a minimum wage of $3 a day, Portes said.

One of those victims was from Mexico City, another was from Brownsville; the other four were local residents.