MOUNDS, Okla.--Two young Church of God members were all set to come home from England on an Aug. 10 flight that would-be suicide bombers had secretly selected as a practice run for blowing up several jetliners over the Atlantic Ocean.

Before a terrorist or terrorists could board the plane, British authorities canceled hundreds of flights and arrested 21 "main players," all of whom were "Muslims and British citizens," in the plot to destroy jets of three U.S. airlines over the Atlantic.

British authorities announced that had the attack eventually succeeded a loss of life on an "unimaginable scale" would have resulted.

Brittney Kurr, 19, and her brother, Raymond Kurr, 18, from Mounds and members of the Church of God Tulsa Fellowship, had embarked on a three-week trip with friends Mike Ellams, 19, and Sue Karas, 18, both from Gloucester, England.

The Kurrs flew in to Heathrow Airport in London from Budapest on Aug. 9 and were set to leave on American Airlines Flight 67 Aug. 10, the same day British authorities say they foiled an attempt by "British Muslims" to "cause untold death and destruction and to commit, quite frankly, mass murder," in the words of Paul Stephenson, a British police official.

Authorities said the "principal characters" planned to smuggle explosives onto jets in hand luggage of three flights, on American, United and Continental planes, from England to New York, Washington and California.

To prepare for the bombings, the 21 people arrested had allegedly scheduled practice runs over the Atlantic for Aug. 10.

When Raymond and Brittney Kurr arrived at Heathrow they immediately began to sense that something was wrong.

"We made it to the airport," Miss Kurr said, "and there were so many people there, it was just so packed.