Security screening bottlenecks at Houston's main airport caused massive delays on Thursday for frustrated travelers trying to flee oncoming Hurricane Rita.

Houston Mayor Bill White, angered by reports of four- to five-hour waits to go through security at Bush Intercontinental Airport, blamed workers at the US Transportation Security Administration.

White, a Democrat, blamed the "failure to show up at work by (110) essential personnel of the federal TSA."

Several factors beyond personnel issues contributed to the backups, which were reduced to 45 minutes by Thursday afternoon, agency spokeswoman Andrea McCauley said.

"We deployed 150 screeners from four different airports across Texas and tried to make up as much as we could of the shortfall," she said.

However, a crush of passengers larger than the Thanksgiving holiday rush, several unticketed passengers trying desperately to get aboard any aircraft and a much higher than normal volume of baggage caused huge lines.

"We did see longer wait times than we'd like to see," she said.

A core group of TSA workers were set to ride out the storm at the airport to get operations running again as quickly as possible, she said.

Flights in and out of Houston were expected to cease some time on Friday as weather conditions deteriorate.