An investigator points at a bullet hole in the window of a cafe after a shooting incident near the Khao San Road tourist area in Bangkok January 11, 2014. [Photo/Agencies]

BANGKOK - Seven people were wounded, one seriously, after gunmen opened fire on anti-government protesters in Bangkok early on Saturday, heightening fears of more violence when protesters try to "shutdown" the capital next week in their long-running bid to overthrow Prime Minister Yingluck Shinawatra.

"Two shootouts occurred in the early hours of this morning at an intersection near the Khao San Road tourist area. Altogether seven people were injured, most of them anti-government protesters. We are still investigating who the gunmen were," said national police chief Adul Saengsingkaew.

One of the injured protesters remains in a critical condition, according to the Erawan Medical Center which monitors Bangkok hospitals.

The incident follows clashes between government supporters and protesters on Friday outside Bangkok that left at least six people injured.

The turmoil is the latest episode in an eight-year conflict that pits Bangkok's middle class and royalist establishment against the mostly poorer, rural supporters of Yingluck and her brother, former premier Thaksin Shinawatra.

At a celebration to mark national Children's Day on Saturday Thailand's army chief, Prayuth Chan-ocha, said he feared an escalation in violence next week.

"I am concerned about security because there will be many people. The violence is increasing...," said Prayuth.

"We can think differently but we cannot kill each other. Please don't use violence."

Many Thais believe the military will soon step in to break the political deadlock, especially if the protests turn violent, and rumours of an impending coup have intensified.

The army has staged or attempted 18 coups in 81 years, but it has tried to remain neutral this time.

The authorities say they will deploy more than 14,000 troops and police on Monday, including police at the main airport, to maintain order in the streets.