国际英语新闻：3 shot dead, 4 wounded in U.S. state of New Mexico

Schultz also said the gunman was a former employee of the Albuquerque-based company which has about 700 full-time employees. But he did not release the name of the shooter.

The cause of the shooting not yet known, while the police said investigations are still underway.

But Schultz said police believe the incident was domestic violence shooting at workplace in nature. Schultz disclosed that the gunman had a history of domestic violence, saying there was at least one previous domestic violence call involving the gunman.

He believes that the gunman was the only killer who acted alone, and that a current employee of the firm, his wife or girlfriend, was the target of the attack.

Police said the man's children, who live out of Albuquerque, were taken into protective custody earlier Monday.

Chris Ramirez, director of communications for Albuquerque Mayor Richard Berry, also said the nature of the shooting is domestic.

"It appears it was some sort of domestic violence situation, but the information is still sketchy,"said Ramirez. "Police are still collecting information from eyewitnesses."

Ramirez said Berry is at the site with executives of Emcore Corporation, a solar photovoltaic and fiber optics manufacturer based in Albuquerque.