D.C. lottery officials confirmed yesterday that a mistake by computer technicians allowed a D.C. Lottery agent to purchase four tickets early Tuesday morning, more than an hour after sales closed for the day. Lottery officials said the accident caused no financial jeopardy to the city's gaming system.

The agent, Linda N. Ray, manager of Sharon's Exxon, a 24-hour gas station at 4501 Benning Rd. NE, said she bought four 50-cent tickets for the Daily Numbers game when she noticed the lottery computer terminal in her business turn on at 12:23 a.m. She said it was the second time in a week the machine, which is programmed to turn on at 6 a.m. and shut off at 11 p.m., had activated after hours.

But on Tuesday, "I keyed in a number just out of curiosity and the ticket came up," she said. She bought three more tickets and generated sales report sheets, which show the time of purchase, she said.

Lottery officials confirmed that Ray called the lottery board on Tuesday morning and alerted them to the incident.

An investigation in under way. Officials said it is the first incident of its kind.

The lottery's computer shuts down from 11 p.m. to 6 a.m. daily. This is supposed to stop all ticket sales by the city's 800 agents. But on Monday night, according to Jeanette Michael, general counsel for the lottery board, special adjustments were being made to the computer after the usual nightly run of sales reports. The adjustments required the computer to be activated, and its operators neglected to disconnect the agents' terminals, she said.

Michael said the computer's internal reporting system showed the after-hours sales and questions would have been raised had the tickets been winners.

"It was simple human error," said Arville Brock-Smith, director of computer operations for the lottery. "The system protected us."