Mexico vowed Sunday to capture the people responsible for the fatal drive-by shootings of two Americans and a Mexican with ties to the US consulate in Ciudad Juarez, and offered "heartfelt condolences" to the victims' families.

"Mexico extends its most heartfelt condolences to the families and colleagues of the two employees associated with the US consulate in Ciudad Juarez and one of their spouses murdered on Saturday," a government statement said, calling calling the shootings a "heinous act."

"Mexican law enforcement agencies will work closely with their United States counterparts to track down those responsible for these killings, so that justice can be served."

The government also vowed not to be deterred from its fight against drug trafficking, which has unleashed much of the violence wracking the country over the past two years.

"The government of Mexico will continue to roll back transnational organized crime and, under the principle of shared responsibility, underscores the need for both our countries to keep working as full partners to guarantee the safety and security of our peoples -- particularly those living in our border communities," the statement here said.

Suspected drug cartel "hit teams" on Saturday gunned down an American consular employee and her husband in the Mexican border city and killed a co-worker's Mexican husband in a separate attack.

The victims -- two Americans and a Mexican -- came under fire in separate locations as they were driving through Ciudad Juarez after earlier attending the same social event, the official said, speaking on condition of anonymity.

The killings marked an ominous turn in the drug violence wracking northern Mexico, and prompted the State Department to announce that Americans working at six US consulates in the border area could opt to send their families away.

US President Barack Obama said he was "deeply saddened and outraged by the news of the brutal murders," his National Security Council spokesman Mike Hammer said.