Cargo trains carrying medical supplies reportedly entered North Korea from the Chinese border town of Dandong twice on Thursday night. 

According to multiple sources familiar with North Korean affairs, the trains traveled from Dandong to the North's Sinuiju, first at 9 p.m. and again at 10 p.m.

Sources said each train had 30 freight cars loaded exclusively with medical supplies.

North Korea and China resumed train-shipping operations in January with the service running only once a day. This delivery marks the first time since then that the train has operated twice in one day.

According to sources, the trains spotted on Thursday were longer than the usual convoys of ten to 15 carriages the past.

This comes as the city of Dandong went into lockdown on April 25 due to COVID-19 and the operation of cargo trains to the North was suspended four days later.

The latest development comes amid a suspected COVID-19 outbreak in North Korea. The regime announced over 100-thousand new fever cases on Friday, raising the accumulated total to over three million.