MEXICO CITY, Mexico (CNN) -- Seven federal police officers were killed Tuesday in northwest Mexico in the latest in a series of drug-related violence, a spokesman for the federal police said.
Mexican police say seven officers were killed and four were wounded in a raid of a home in Culiacan.
Another four officers were wounded and a civilian was killed during the incident, which occurred as police were conducting a weapons and drugs raid on a home in Culiacan, police spokesman Armando Arteaga said.
Upon arriving at the house, the officers were fired upon and a grenade was thrown at them, Arteaga said. Authorities arrested two people, including a minor, and confiscated seven AK-47s and dozens of ammunition clips.
Photographs taken by Mexican police showed the walls of the house pockmarked with bullets and the small arsenal of confiscated arms in police custody.
The body of an unidentified man lay face up in a pool of blood on a cement floor.
Culiacan, a city of more than 600,000 people in the state of Sinaloa, has become a key battleground in Mexico's drug war. Map: See where Culiacan is »
In recent days, President Felipe Calderon has sent 2,000 federal police and army troops to Culiacan in an effort to stem the flow of drugs through the city.
But Calderon's campaign has been met with a vicious response that has resulted in more than 1,000 people dead in drug-related violence since the beginning of the year. The victims include Mexico City's top federal police chief as well as four other federal police killed in an ambush this month in Culiacan.
Pitched battles between rival drug gangs, assassinations of police officers and ambushes on city streets have made life hell for many residents of Culiacan. Watch CNN's Harris Whitbeck accompany a drug raid »
Some 300 tons of cocaine are estimated to pass through Mexico to the United States each year, and Mexico is considered the largest foreign supplier of crystal methamphetamine to the United States.
A U.S. counternarcotics official predicted Calderon's battle will be a long, bloody and uphill slog. But Police Commander Gen. Jose Antonio Guzman, speaking before Tuesday's incident, was more optimistic.
"I feel we are making progress," he said. "Let's see how long it lasts."
CNN's Harris Whitbeck contributed to this report.