SANTA CLARA, Calif. (AP) _ Federal agents seized more than 74 million rounds of illegally imported assault-type ammunition Wednesday _ enough bullets to fill eight to 10 railroad cars.

The ammunition confiscated from a weapons importing business had false papers and came from an embargoed country, the Customs Service said.

Agents would not say what country the shipment was from.

No arrests were made, but the investigation was continuing.

Michael Donofrio, a supervisory agent with the Customs Service, estimated that it would take 23 tractor-trailer trucks to haul away the ammunition, worth $24.5 million wholesale.

The ammunition is believed to have entered the country over a period of time through the Port of Oakland, Donofrio said. The investigation began a month ago, after Southern Pacific police reported the theft of some boxes of ammunition from a rail car.

The bullets would fill eight to 10 railroad cars, said Ed Gleba, a spokesman for the Bureau of Alcohol, Tobacco and Firearms in San Francisco.

It is not illegal to possess or sell 7.62 mm ammunition, which is used in assault-type weapons, including the AK-47, but it is illegal to import it from certain countries.

Santa Clara is about 40 miles southeast of San Francisco.