Ecuador was hit with an hours-long nationwide blackout on Wednesday that left the South American nation’s 17 million people without power.

The blackout — which affected hospitals, homes, and a major subway system — was caused by maintenance and transmission issues in the country’s electrical system, authorities said.

“The outages we had today were due to a lack of investment in maintenance, new electrical transmission, and the protection of the electrical transmission infrastructure,” Public Infrastructure Minister Roberto Luque told a news conference on Wednesday.

As of Wednesday night, energy had been restored in 95% of the country, according to the government.

Ecuador has been struggling with an energy crisis for years. The latest saw Ecuadorean President Daniel Noboa declare an energy emergency in April and order eight-hour nationwide power cuts amid a drought that affected power generation.

In the capital city of Quito, a CNN team saw two hospitals, including a children’s medical center, lose power during the blackout. Both hospitals were able to rely on electricity from their generators shortly after the cut began.

In the nation’s largest city of Guayaquil, the blackout also briefly affected two other hospitals. “The power was cut but we have our own (generators),” a doctor from Guayaquil’s Luis Vernaza hospital said. CNN reached out to the country’s Health Ministry to ask if other hospitals were affected.

Guayaquil residents faced the outage amid 90 degrees Fahrenheit (32 Celsius) heat. “It’s unbearable, it’s so hot and humid, and we can’t use an air conditioner or a fan,” one resident told CNN.

“On top of this, the water is not running,” the resident added.

Service was interrupted on Quito’s subway system due to the blackout, with the capital’s Mayor Pabel Muñoz saying the outage was so “significant” it had affected the subway despite it using “an isolated (electrical) system.”

Infrastructure Minister Luque said the blackout could have been avoided had Ecuador carried out an investment plan to “safeguard the infrastructure in both generating (power) and the transmission” after a similar power outage took place in 2004.

Wednesday’s blackout is not related to the country’s energy crisis from last April, Luque said.

“The outages we had in April were due to lack of investment in new (power) generation and in maintenance of the (power) we have,” Luque said.

This story has been updated with additional developments.