TAIPEI -- Taiwan's electricity supply resumed on Thursday evening following several hours of rotational blackouts across the island.

Around 4 million households were affected after the Hsinta Power Plant in the city of Kaohsiung was unable to distribute energy due to a failure of the electricity grid, according to the Taiwan Power Company.

The rotational blackouts started around 3 pm, with the power supply restored at about 8 pm after emergency repairs.

Public criticism is mounting as the blackouts have subjected people to hours of sweltering heat, caused transportation chaos and left some residents trapped in elevators.

Local authorities apologized for the blackouts at a press conference on Thursday evening, and promised to provide a more thorough explanation about the incident on Friday.

Taiwan has suffered from an unstable power supply in recent years. In August 2017, six units tripped at the Datan Power Station in the city of Taoyuan, causing large-scale power outages in 17 counties and cities, affecting 6.68 million households.