Six members of the Flying Doctors, a Northern California volunteer medical group that makes monthly trips across the Mexican border, died Saturday when their small plane crashed just outside Ensenada, Mexico.
They were flying from San Ignacio, where the organization runs a clinic, to Ensenada for a seminar.
Among the victims were physicians Marvin Weinreb of Oakland and Edith Loewenstein of Walnut Creek, both board members who had long been active in the group.
"They were very, very dedicated . . . good people," said treasurer Pat Lewis.
Mexican authorities did not know the cause of the crash, which occurred at 10:30 a.m. about nine miles south of Ensenada in a sparsely populated area.
The two-engine Cessna 320, piloted by Weinreb, went down as it was approaching the military airport in Ensenada.
The 25-year-old Flying Doctors group is one of several organizations that provide volunteer medical care to Mexican villagers.
"It's really a tragedy because they came to help people with few resources and help people who don't have access to basic services," said Indira Mata, a spokesman for the city of Ensenada, which co-hosted the seminar.
Lewis said the Ensenada conference was the first large gathering of the group in several years.
Flying Doctors has more than 400 members, including physicians, nurses, dentists and others.
In addition to Weinreb and Loewenstein, the other victims were identified by Mexican federal police as co-pilot Michael David Cala of Foster City; Briand F. Mitchell of San Jose; Deborah Wayne, 48, of Lemon Grove; and Helen Goldstein, 68, address unknown.
In May, three volunteers from another medical charity, the Flying Samaritans, died when their small plane crashed south of Tijuana.
Times staff writer Ken Ellingwood contributed to this story.