Things happened faster than anticipated yesterday as Mary Loeck and her husband John set out for Fairfax Hospital shortly after 8 a.m. There was no panic after her labor pains started but, by the time the couple got to their car and before he could start the engine, a baby started arriving.

"I was terrified," recalled the 25-year-old mother. Fairfax County medics were summoned to their home at 8862 Glenridge Ct. near Wolf Trap Farm Park and arrived just in time to deliver a baby boy.

Minutes later, with mother and son en route to the hospital in an ambulance, medics helped deliver a twin brother.

Later, with Mrs. Loeck resting and the twins sleeping, doctors declared young Jonathan Francis Loeck and Brady Willis Loeck in good condition even though they were delivered five weeks prematurely.

Mrs. Loeck said doctors told her several weeks ago to expect twins. "I was shocked then," she said, but she was even more surprised by their quick arrival yesterday.

John Loeck, manager of a telephone business, had shouted to neighbors who were babysitting the couple's 2 1/2-year-old daughter to call an ambulance when he realized that births were imminent.

How did he react to it all? "He took it pretty well, he was wonderful," said the new mother of twins.