A new earthquake in Haiti sent people fleeing into the streets, according to reports.

The tremor, which occurred early Wednesday morning and had a magnitude of 6.1, happened 35 miles west-southwest of Port-au-Prince. The extent of new injuries and damage has not yet been reported.

The U.S. Geological Survey (USGS) is reporting that the shake was a strong aftershock associated with last week’s major earthquake.

Experts from the USGS National Earthquake Information Center said that when large earthquakes happen, aftershocks occur because a fault line is readjusting. Aftershocks may be felt in Haiti over the next few weeks or maybe longer.

Reports indicate that people camping out in the streets since last week’s quake panicked during the aftershock. Many, who have been left homeless, again feared for the worst.

Some 12,000 U.S. military personnel are on the ground in Haiti. The USNS Comfort arrived at the island on Wednesday. The hospital ship is providing more beds for injured earthquake victims as well as a place to perform several much-needed surgeries.