MEXICO CITY, FEB. 2 -- Armed men believed to be Colombian guerrillas kidnapped three American missionaries from a remote village in the rugged southeastern Panamanian province of Darien late Sunday. There has been no word from the kidnappers.

The wives and children of the missionaries witnessed the kidnappings in the village of Pucuro but escaped unharmed with the help of local Kuna Indians, said Nancy Mankins, wife of kidnapped missionary David Mankins. Speaking by telephone from Panama City, she declined to give other details, referring all questions to the New Tribes Mission headquarters in Sanford, Fla.

Mel Wyma, spokesman for New Tribes, identified the three kidnap victims as Mark Rich, 23, Rick Tenenoff, 36, and Mankins, 43. Wyma said there are no clues as to why the three were seized.

Margaret Gaspar, a friend of the Mankins family in Susanville, Calif., quoted Nancy Mankins as saying in a telephone conversation today that the kidnappers did not identify themselves but that they were "extremely well organized and polite."

Mankins told Gaspar the kidnappers, who appeared to be Colombian guerrillas, bound the three missionaries, asked them if they were on any medication that they should take with them, and then told the wives not to worry. The kidnappers promised not to harm the hostages and said while departing, "You will be hearing from us."

If it is verified that the armed men are Colombian guerrillas, the kidnappings would be the first such cross-border incident in Panama directed against Americans. Americans and other foreigners have been kidnapped for ransom by guerrillas in Colombia.

Wyma said a small group of New Tribes missionaries were kidnapped in rural Colombia in November 1985 by members of the Armed Revolutionary Forces of Colombia, but were released unharmed and unconditionally that month.

Panamanian government spokesman Victor Acosta said military helicopters and police search units had flown to Darien and the Colombian army had pledged to comb its side of the border.

Panamanian authorities have said the border region, known as the Darien Gap, is frequented by Colombian guerrillas seeking relaxation without fear of pursuit by the Colombian military.

According to recent reports from Darien, the area around Pucuro is traversed by Colombian drug traffickers smuggling cocaine and heroin into Panama. Puerto Obaldia, a Panamanian port on the Caribbean coast about 50 miles northeast of Pucuro, is regarded by Panamanian authorities as an important transshipment point.

Mankins and Tenenoff reportedly have been working with Kuna Indians in Darien for eight to 10 years, while Rich and his wife began about a year ago. Mankins and Tenenoff have two children each. Wyma said about 80 New Tribes missionaries are working throughout Panama and that the group has missions in 22 other countries.

Wyma said he told a Colombian radio station heard in the region "that our people were out there to help and teach the Indians, to learn their language and try to assist these people any way they could." Special correspondent Berta Thayer in Panama City contributed to this report.