Mexican President Felipe Calderon says he "deeply regrets" the shooting attack on a U.S. Embassy vehicle by federal police last week, and promises a "thorough investigation with all rigor and severity."
Calderon says that whether the shooting was "due to complicity, a lack of training, a lack of trustworthiness, these events are unacceptable."
He says "we cannot allow these things to happen."
Calderon made the remarks Tuesday at an anti-crime conference in Mexico City attended by U.S. Ambassador Anthony Wayne.
Two U.S. Embassy personnel suffered non-life-threatening injuries on Friday when federal police opened fire on their bullet-proof sport utility vehicle on a rural road just south of Mexico City.
Prosecutors are holding 12 federal agents under house arrest pending possible charges of abuse of authority.