City building inspectors are investigating the partial collapse of a walkway late Tuesday at a Makiki apartment complex that prompted the evacuation of 18 residents and sent chunks of concrete raining down onto a walkway below and three cars in a ground-level garage.

No one was injured in the collapse, which happened just before midnight at the Hawaiian Holiday complex at 1420 Wilder Ave.

But the incident did leave many residents shaken.

"I thought it was an earthquake," said Queeny Raquel, 25, who was eating dinner in her boyfriend's unit at the complex when pieces of concrete fell from the underside of a third-floor walkway. "It just sounded like a loud crash."

Raquel's boyfriend, David Pascual, ran out of his unit when the portion of walkway fell. The area where the walkway gave way is just feet from his front door.

"We were in awe at what we saw," said Pascual, 27. "It's pretty scary."

Pascual and the 17 other residents who were evacuated were given a little time to grab clothes and other belongings before they were ushered outside by firefighters. A yellow "x" was drawn on their doors to signify the units were empty.

Only one section of the four-story walk-up building was evacuated. Residents in other units were allowed to stay.

The American Red Cross of Hawaii put three of the evacuated residents up in hotels; the rest stayed with family or friends.

Yesterday morning, the residents who had to leave were not able to return to their units to retrieve belongings.

It's unclear when they'll be able to get back in because getting to their units would require passing over the portion of collapsed walkway.

A section of the underside of the third-floor walkway, about 12 feet long, broke loose and fell onto the second-floor walkway and cars in the garage.

City Planning and Permitting Department inspectors went to the complex yesterday to investigate the collapse, and look at other conditions at the apartment building.

City spokesman Bill Brennan said inspectors were also at the complex onon Sept. 3 and issued building code violations for deficiencies in units 28 and 33. He had no information on the nature of the deficiencies.

Darryl Wong, the building's landlord, declined to comment on maintenance questions about the building.

Wong visited the building yesterday to view the damage and try to start clean-up work, and said he didn't know how the walkway collapsed.

"It's probably just old age. Who knows?" Wong said.

He said he would try to accommodate the 18 evacuated residents in other rental units he has.

The Wilder Avenue building was built in 1962, and has 38 units.