A group of suspected illegal immigrants was being questioned early Tuesday after federal officials forced their single-engine plane to land here.

The Cessna (search) carried at least four suspected illegal immigrants who were detained along with the craft's pilot by homeland security officials in connection with a possible smuggling operation, according to newspaper and broadcast reports.

A police dispatcher said federal authorities forced the craft to land just before 10 p.m. Monday at Stinson Municipal Airport (search), a few miles south of downtown San Antonio.

"They brought a plane down. They are holding it," a San Antonio Police Department dispatcher, who spoke on condition of anonymity, told The Associated Press. "They asked us to assist them. The FBI is handling it now."

Representatives of the Homeland Security Department (search), FBI and Federal Aviation Administration (search) did not return telephone calls early Tuesday from the AP.

Online records of the Federal Aviation Administration show the 20-year-old plane is co-owned by Afzal Hameed of Dover, Del. The other co-owner is listed as Alyce S. Taylor, but no address is given for her.

The FAA records state that the plane's last three-year registration was filed in 1999, and that the agency received no response in 2002 after mailing new registration forms to Hameed.

Capt. Jeff Humphrey, San Antonio police special operations commander, told the San Antonio Express-News in Tuesday's editions that the five suspects were under investigation in connection with a smuggling operation involving Chinese nationals.

The newspaper said the five had been flying south of San Antonio when they were intercepted and ordered to land. Federal agents and San Antonio police surrounded the plane after it landed.

Federal authorities said the plane was flying in American airspace illegally and that those aboard the craft appeared to be Chinese, according to San Antonio television and radio station WOAI.

The Express-News said federal Immigration and Customs Enforcement (search) officials asked for backup from San Antonio police, who provided a Chinese linguist to translate for the two male and two female passengers.