(CNN) -- A Michigan woman who fell asleep during a flight and woke up locked in an empty plane filed a lawsuit Thursday against United Airlines and a partner airline.

Ginger McGuire, 36, spent nearly four hours on the plane after United Express Flight 8080 landed before she was discovered by a cleaning crew, according to the complaint filed in Wayne County Circuit Court.

"Waking up on an empty airplane and not being able to get out was very horrifying. It's a very dramatic word, but it was a little much," McGuire said at a news conference. Attorney Geoffrey Fieger, of Fieger Law in Southfield, Michigan, is representing McGuire.

United Airlines and Trans States Airlines, the carrier operating the United Express flight, are investigating the incident.

Trans States spokesman Fred Oxley said he could not comment on the suit's allegations without reviewing the documents.

"On the incident itself, I can tell you that it did occur and certainly that investigation is ongoing," Oxley said.

"Our procedures would call for the flight attendant before leaving the aircraft to do a sweep of the aircraft to ensure that there are no passengers left on. So our focus is certainly on whether or not that procedure was accomplished in this case," he said.

United Airlines said in a statement that it is working with Trans States "to investigate the cause and remedy the situation with the customer."

McGuire is seeking between $25,000 and $75,000 in the suit which alleges negligence, infliction of emotional distress, false imprisonment and breach of contract.

The complaint outlines a series of delays that led up to McGuire falling asleep on the airplane. McGuire was originally scheduled to leave Detroit, Michigan, at 6 a.m.Monday with a brief layover in the Washington area before continuing to Philadelphia, Pennsylvania. She didn't leave Washington for Philadelphia until 11:40 p.m.

United Express Flight 8080 arrived in Philadelphia just before 12:30 a.m. Tuesday. McGuire was asleep when the plane landed and passengers and crew disembarked, the complaint said.

When a cleaning crew discovered McGuire four hours later, it alerted the Transportation Security Administration and McGuire was "wrongfully detained and interrogated," the complaint alleges.

James Harrington, an attorney working with Fieger on the case, said the incident highlights a major safety issue.

"If my client, a completely unassuming person who was just exhausted ... and falls asleep, could go undetected, what if somebody is really trying to go undetected?" Harrington said.

"All the explanation could be is that it was just pure laziness. There's no other explanation or excuse," he said.