An earthquake today struck Mexico City, about 60 miles northwest of Acapulco, and it now considered as the second biggest quake that hit the region within this month, the U.S. Geological Survey said.

Mexico City's downtown area was rocked by an earthquake today, about 170 miles northeast of the epicenter, in Guerrero state.

According to USA Today, no immediate reports of serious damage or injuries in the capital were documented following the tremor.

El Universal reported that in Tecpan de Galeana, about 9 miles from the epicenter, a highway bridge that was being repaired due to the damage caused by the flood last fall and a strong quake nearly three weeks ago gave up and come crashing.

The city mayor said Thursday's earthquake was ferocious and said it led to a "wave of panic" amongst the residents, especially when some roofs collapsed.

A reporter tweeted about the earthquake that struck Mexico City today, saying the tremor lasted for nearly 40 seconds in the capital.

Office workers reportedly streamed into the streets while the city had a 68-second warning.

"It was very scary. Some of my colleagues suffered panic attacks because the buildings moved," Carmen Lira, a secretary working for a company located in the area, said. "It felt very strong."

Although initially, the quake was said to be at 6.8 magnitude, the USGS has downgraded it to 6.4.

No tsunami threat was recorded based on the initial indications made by the Pacific Tsunami Warning Center.

Just last April 18, thousands rushed out of their offices and homes when a magnitude 7.2 quake shook several areas in central and southern Mexico. No major damage and serious injuries were reported out of the incident.