Mexico City (CNN) -- Mexican authorities moved Saturday to tighten their communication about Friday's shooting of two U.S. Embassy personnel by federal police as the Americans drove in their SUV south of the capital with a Mexican Navy captain.
Federal police spokesman Ramon Salinas told CNN that he has been asked not to comment or release any new information about the investigation. He said all information would come from Los Pinos, the official residence of President Felipe Calderon.
But the president's office did not respond to a request for comment.
The incident occurred at 8 a.m. Friday, when the two embassy employees and the Mexican were en route through the mountainous area to a navy facility in the municipality of Xalatlaco, according to a statement issued Friday by the Mexican Navy, which gave the following account:
The black SUV bearing a diplomatic license plate had just left the main highway that connects Mexico City with Cuernavaca and were driving on a dirt road that connects the small towns of Tres Marias and Huitzilac when a vehicle approached. When the occupants brandished firearms, the driver of the diplomatic vehicle tried to evade them and return to the main highway. At that point, the occupants sprayed bullets into the black SUV with diplomatic plates.
Moments later, another three vehicles joined the chase and fired shots at the embassy vehicle. The Mexican in the SUV called for help from the Mexican Navy personnel in nearby El Capulin who arrived after the shooting had ended and cordoned off the area.
Federal police, who were in the area working on a criminal investigation, participated in these acts, the statement said, but did not specify which vehicle or vehicles they were in.
Both embassy employees were taken -- under federal police guard -- to a hospital.
Photographs of the SUV showed the embassy vehicle pockmarked with more than a dozen holes and at least three of its tires flat.
The federal police officers involved were being questioned by authorities to establish what happened.
In a statement issued late Friday, the U.S. Embassy described the Mexican as a Navy captain and said the three individuals were en route to a training facility when they were ambushed.
"The vehicle attempted to escape, was pursued and sustained heavy damage," the statement said. "They called for assistance from the Mexican armed forces, who responded. The two U.S. wounded personnel were taken from the scene, given medical treatment and are in stable condition. The Mexican Navy captain sustained no serious injuries."
The Mexican government said those members of the federal police who fired on the vehicle have been detained, the U.S. Embassy statement said.
It added that the Mexican government "has stated it will conduct a full and thorough investigation of this incident."
Also Friday, State Department spokeswoman Victoria Nuland said, "We are working with Mexican authorities to investigate an incident this morning in which two employees of our embassy in Mexico City came under attack by unknown assailants. They are receiving appropriate medical care and are in stable condition. We have no further information to share at this time."
At Drug Enforcement Administration headquarters in Washington, a spokeswoman said the agency was not involved in the case.
The long-term impact of the shooting will depend on how aggressively the Mexican government pursues the investigation, said Sylvia Longmire, a drug war cartel analyst and author of "Cartel: the Coming Invasion of Mexico's Drug Wars."
"I'm somewhat skeptical that anyone will be brought to justice in this attack," she told CNN Saturday. "Remember, nobody knows who shot the Americans. They're still going to have to do ballistic reports."
Though federal police have a reputation for being among the least corrupt of Mexico's security forces, "I'm concerned that there is a potential for this to get swept under the rug," she said.
CNN's Tom Watkins, Nick Valencia, Jill Dougherty, Rafael Romo and Terry Frieden contributed to this report.