SANTO DOMINGO, Dominican Republic (AP) — The Dominican Republic was briefly hit by a country-wide blackout Monday in the second such outage in the past three months, triggering concerns about the stability of the Caribbean nation’s power grid.

Monday’s blackout snarled traffic, disrupted public transportation and forced some businesses to close as crews scrambled to restore power.

The country’s main power plants abruptly stopped supplying energy before noon, causing all other plants to shut down, according to the state-owned Dominican Electricity Transmission Company. But by mid-afternoon, the system was operating at nearly 30% of its capacity, Energy Minister Joel Santos said.

“Essential services such as hospitals, drinking water systems, mass transit and airports are operating with their backup systems,” he said.

Santos said that the failure was caused by a trip in a transmission line switch, which caused the system to go into protection mode.

A massive blackout that hit the Dominican Republic last November was blamed on human error during line maintenance work.