Video obtained by Reuters showed a crowd on Saturday (October 17) at Lat Phrao intersection, a major road junction in the heart of Bangkok. That video has been viewed more than 1.3 million times on Twitter.
Thais have demonstrated for three months demanding to curb the powers of the monarchy and Prayuth's removal from power.
Many protesters said they were stirred to action after water cannons were used on Friday (October 16) at a youth-led demonstration which included many children.
At a university in Khon Kaen, demonstrators shone lights and sang 'Always', a song by Thai singer Pongsit Kamphee.