(Adds details in paragraphs 3-5) TIJUANA, Mexico, April 18 (Reuters) - Police battled an armed group of drug traffickers in this northern border city on Wednesday in a series of shootouts that left two policemen and one drug gang member dead, witnesses and authorities said. A first gunfight started at the main Tijuana bus station when police stopped three vehicles as part of a drug clampdown and traffickers aboard open fire. The criminals fled but one was injured in the hail of bullets and police took him to a hospital for treatment. The drug traffickers later stormed the hospital to try and retrieve the injured gunman and another shootout started. TV images showed scenes of chaos at the hospital with dozens of armed police hunting down traffickers inside the building. Frightened patients tried to flee but were forced to lie on the ground to avoid any of the escaping criminals. After a tense stand-off, five of the armed gunmen were arrested. No patients in the hospital were injured. "I can confirm the death of two policemen and one of the criminals at the scene of the first gunfight," Tijuana police chief Jaime Niebla told reporters.. Mexico has seen a wave of drug-related violence recently and President Felipe Calderon has sent thousands of troops onto the streets of many cities to wage war against drug cartels. Much of the violence is between rival cartels seeking to grab control of drug routes to the United States. To date this year, drug-related deaths number more than 600. Separately, an unknown assailant tossed a grenade into the offices of a northern Mexican newspaper a day after gunmen snatched a reporter from a nearby city, part of a campaign against the media by drug gangs. The grenade exploded inside the offices of Cambio newspaper in the northern city of Hermosillo on Tuesday night, breaking windows and startling reporters. Nobody was injured, newspaper director Roberto Gutierrez told Reuters. The attack came a day after gunmen in the border city of Agua Prieta, like Hermosillo in the state of Sonora, snatched a crime reporter investigating the country's bloody war between rival drug cartels. Mexican journalists reporting on drug gangs are often targeted by traffickers, but attacks on the media appeared to mount after Calderon launched his crackdown. Gunmen shot dead a reporter from Mexican television network Televisa earlier this month in the Pacific resort of Acapulco, which has become a major battleground for gangs. More than 2,000 people were killed last year as Mexico's notorious Gulf Cartel battled over production, routes and markets with an alliance of traffickers from the state of Sinaloa, which borders Sonora to the south. (Additional reporting by Greg Brosnan)
