Lou and Patty Herzog, who became leaders in an anti-drunk driving group after their youngest daughter was killed by an intoxicated motorist, have an added reason for their advocacy: A second daughter was seriously injured last week in an accident believed to have been caused by a drunk driver.

Debbie Herzog, who also was active in the Northern Virginia chapter of Mothers Against Drunk Driving before moving to Florida three months ago, wound up with two broken legs and facial injuries in the two-car crash last week near Tampa. The other motorist was arrested and charged with driving under the influence and other counts, according to a Hillsborough County law enforcement officer.

"You never think it's going to happen once, but when it happens twice you get a little gun-shy," Lou Herzog, 54, said yesterday from his daughter's hospital room in Tampa.

"It's unbelievable. We just can't fathom it -- that fate could deliver this second blow," said Patty Herzog, 53, who was also with her daughter yesterday.

Debbie Herzog, 25, was returning home from a shopping trip, driving along a two-lane highway at 8:50 p.m. Thursday, when an oncoming car crossed the center line and struck her 1985 Datsun, according to Lt. Fred Wheeler of the Hillsborough County Sheriff's Office. In addition to the alcohol charge, Wheeler said, the driver of the 1979 Pontiac was charged with leaving the scene of an accident in which there were injuries and with driving with a suspended license.

Reynaldo Garza, 31, of Dade City, Fla., lost his driving privileges in December because he failed to pay a traffic fine, Wheeler said. He said the accident was still under investigation.

Patty Herzog said her daughter was lodged inside the crumpled vehicle for an hour and 45 minutes before rescue workers could get her out. Her injuries included a broken cheekbone and broken legs, one a compound fracture that could take up to nine months to mend, her mother said.

Instead of beginning a management training program at a Tampa bank, Debbie Herzog has had to put her plans on hold for a year, and she will be returning to live with the family in Fairfax County, said her mother. The Herzogs also have a 27-year-old daughter, she said.

Their youngest daughter, Susan, 18, was killed on New Year's Eve in 1981 by a drunk driver. Reeling from her death, the Herzogs channeled their anger and energy into the then-new Northern Virginia chapter of Mothers Against Drunk Driving.

Until about a year and a half ago, the MADD chapter had 350 members, said Lou Herzog, who ended a three-year stint as president of the organization two weeks ago. Today, after an extensive television campaign, the group has 18,000 members, he said.

Stuart Schmid of McLean is the new chapter president. Schmid said that members contribute a minimum of $20 to join the group and that a "small percentage" contribute their time.

He expressed dismay over the latest misfortune to hit the Herzogs, but not surprise. In Virginia alone, about 500 people are killed and 15,000 injured in alcohol-related crashes every year, he said.

The Herzogs continue to be involved in anti-drunk driving campaigns, with Lou Herzog serving as chairman of MADD's state coordinating committee and Patty Herzog working as the victim assistance chairwoman in the local chapter.

"We just simply can't believe it," said Patty Herzog.

"All the work that we have put into MADD did not help our daughter."