Passenger accidentally allowed on Atlanta airport tarmac March 5, 2013 -- Updated 0212 GMT (1012 HKT) Officials are trying to find out how a woman got through security and ended up on the tarmac at the Atlanta airport last month. A traveler trying to make an early morning flight accidentally parked in a Delta employee lot She says she was allowed to get on an employee bus without being asked for identification Transportation Security Administration is investigating how this happened (CNN) -- How did Shannon Reynolds make it through several layers of security unquestioned and end up on the tarmac at Hartsfield-Jackson Atlanta International Airport? That's what Delta Air Lines, the Transportation Security Administration and the Atlanta Police Department are trying to figure out. Around 5 a.m. on February 23, Reynolds told CNN she was simply trying to park at an off-site parking lot in time to catch a flight on Spirit Airlines to Fort Lauderdale, Florida, then on to Costa Rica. She didn't notice she was pulling into a Delta employee parking lot, where she told CNN she was waved through two security check points and allowed to park there. Wearing a sundress and carrying her suitcase, she got on a Delta employee shuttle without being asked for identification. None of the employees on board was wearing a uniform, she said, so she says she didn't realize it was for employees only. It was only when the shuttle drove onto the airport tarmac near Terminal C that Reynolds says she realized she wasn't supposed to be there and told the driver. She was still allowed to get out of the bus onto the tarmac. A ramp agent used his badge to take her up the stairs into the airport and into the passenger area, where someone finally stopped her and asked for her badge. That started the investigation into how she had made it so far without being checked. In the police report filed on the incident, the ramp agent she followed into the concourse said he assumed she was an employee because of all the checkpoints she had to pass. "Airports are responsible for implementing security programs that restrict access to secure areas," said TSA spokesman David Castelveter in a statement. TSA is conducting an investigation to determine how an individual without proper credentials accessed the secure area of Hartsfield-Jackson Atlanta International Airport via an airline employee parking lot. Delta is re-emphasizing the checking of employee identification at Delta employee parking lots, according to the airline. "We have taken aggressive action with our security vendors at the parking lot to emphasize that all security procedures, especially verification of credentials, are strictly adhered to," said Delta spokesman Morgan Durrant in a statement. The police report states that Reynolds "was transported back to her vehicle and allowed to move her car" from the parking lot, noting that the delay caused her to miss her 6:30 a.m. flight. Reynolds told CNN she was able to catch a later flight to Costa Rica, from where she recently returned.