BEIJING (AP) — The swaying of a 70-story skyscraper in the southern Chinese city of Shenzhen was the result of winds causing vibrations on a roof-top mast intended for lightning protection and for guiding aircraft, authorities said Thursday.

The government of the business and technology hub said the SEG Plaza was considered safe and crews were removing the mast and using other methods to provide its functions.

Scores of experts were brought in from around China to investigate the cause of the swaying and assess the building's safety. China has experienced a construction boom in recent years, along with the graduation of record numbers of engineers and project managers.

In the May 18 incident, offices and shops in the building began swaying but there was little damage. The swaying prompted the building’s evacuation and a stampede of pedestrians nearby.

Owners of businesses in the 20-year-old building will be allowed to return “as soon as possible,” the city government said.

The building’s first 10 floors are an electronics market and office space takes up most of the rest, topping out at more than 300 meters (about 1,000 feet) tall with a helipad on its roof.

The incident prompted the U.S. Consulate in the nearby megacity of Guangzhou to issue an advisory urging citizens to avoid the plaza and surrounding area because of “inadequate information to assess the safety risks” and to stay away until authorities sounded the all-clear.

Sitting on the border with the semi-autonomous region of Hong Kong, Shenzhen was transformed from a sleepy fishing village in the 1970s to a thriving center of the electronics industry, with some of China’s flashiest architecture and most expensive real estate.