An Earthquake of magnitude 6.4 shook Puerto Rico early Monday morning, causing only minor damages in some places, NBC News reported.

The earthquake is reportedly one of the largest to hit the U.S. territory in recent years, but caused minor damages, including some power outages, and cracked floors. It struck just after midnight and was very shallow at a depth of 17.7 miles below the seabed, the Associated Press reported citing the U.S. Geological Survey.

There were no injuries reported.

Gisela Baez Sanchez, a geologist with Puerto Rico's Seismic Network, told the AP that at least 70 aftershocks have been reported since the Earthquake, with at least three of a magnitude 3.5 or greater.

"All of Puerto Rico is in a seismic danger zone," she said. "We have to be prepared."

In some areas along the north coast broken windows, a busted a water line and cracked floors and walls were reported. In the north city of Bayamon on the island, some power outages occurred.

"The damages have been minor," Carlos Acevedo, spokesman for Puerto Rico's emergency management agency, told the AP. "No one has required our services."

However, according to the AP, Puerto Ricans are criticizing the island's government on social media for not issuing an emergency alert immediately after the quake. Authorities said they would have sent an alert immediately if people had been at risk of a tsunami.

The Pacific Tsunami Warning Center initially said the earthquake could trigger a small local tsunami. But no tsunami was generated, according to the U.S. National Weather Service Caribbean Tsunami Warning Program.

Sanchez said that although Puerto Rico experiences small earthquakes daily - so small that people cannot feel them - it is rare for bigger quakes to strike the island. In recent years, bigger earthquakes to hit the island included a 5.4-magnitude one that shook the U.S. territory in March 2011 and another one of the same magnitude that struck on Christmas Eve in 2010.

Baez said the earthquake on Monday occurred along a fault previously generated by two tectonic plates crashing into each other.