MEXICO CITY, July 15 (Reuters) - The Mexican government said on Tuesday it was nearly tripling the police presence in Sinaloa state after hitmen killed 20 people and took hostages in various attacks by criminal gangs over the last week.

More than 300 people have died in drug-related violence so far this year in Sinaloa, about a fifth of the 1,700 people killed in cartel battles across Mexico as rival gangs fight each other amid an army-led government crackdown.

The government is raising the number of intelligence agents and police officers in Sinaloa to 2,000 from 740. The state, home to Mexico's most-wanted kingpin, Joaquin "Shorty" Guzman, is one of the most affected by drug violence.

On Saturday, six armed men caused pandemonium in the Pacific port city of Mazatlan by taking refuge in a shopping mall after killing a police chief when he resisted their attempt to kidnap him.

The attackers took some 40 people hostage in a restaurant while they negotiated their escape.

In an incident on Sunday, a group of hitmen sprayed four cars with bullets on a busy street in the city of Guamuchil, killing eight youths.

Last week, hitmen killed 11 people in the Sinaloa capital of Culiacan in two daylight shootouts. (Reporting by Cyntia Barrera Diaz; Editing by John O'Callaghan)

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