Thai police defended their use of force against protesters as a necessary public safety measure, as the capital Bangkok braced for more demonstrations on Wednesday to demand the prime minister's removal for mismanaging a coronavirus crisis.
Police fired tear gas, water cannon and rubber bullets on Tuesday to disperse protesters gathered near the residence of Prime Minister Prayuth Chan-ocha to show their anger over an outbreak that has seen record deaths in recent days.
Thousands of protesters drove in a convoy of cars and motorcycles through Bangkok, stopping at locations linked to cabinet members or supporters of Prayuth, who has defended his strategy to fight the virus.
Police said nine officers were injured, one by gunshot to the leg, while the other eight were hurt by firecrackers, rocks and shrapnel from homemade bombs made using ping pong balls.
At least two police traffic boxes were set ablaze and other public property damaged, police said.
"Police decided to use tear gas, water cannon and rubber bullet because we considered that if we don't, there will be more damage," Bangkok police chief Pakapong Pongpetra told a news conference.
Pakapong said 48 people were arrested including 15 youths, and 122 motorcycles were confiscated.
Protesters have called for another march to Prayuth's residence on Wednesday.
The youth-led movement, which drew broad support during months of large and frequent rallies last year, has seen a recent resurgence coinciding with country's worst Covid-19 outbreak yet, which has accounted for the overwhelming majority of Thailand's more than 788,000 cases and 6,700 deaths.
Several core leaders remain in detention awaiting trial for sedition, among other offences.