Colorful drones lit up the night sky in South Korea in a stunning tribute to front-line workers and message of encouragement for residents battling the coronavirus pandemic.

Three hundred unmanned devices were used in the 10-minute light show over the Han River in Seoul on Saturday, which wasn’t announced beforehand to discourage large crowds from gathering, CNN reported.

The drones were used to create images of the South Korean flag and safety measures, including washing hands, wearing face masks and practicing social distancing.

The show was capped with the drones forming the message “Thanks to you” with a heart and then “Cheer up, Republic of Korea.”

South Korea has seen 13,293 confirmed cases of COVID-19 and 287 deaths as of Thursday, according to the country’s Center for Disease Control and Prevention.