Security forces and agitated protesters faced off at a major intersection on Friday after bloody grenade attacks rattled Thailand’s chaotic capital — a scene of tense, weeks-long confrontations between die-hard demonstrators and a wavering government.

The late-night attacks killed at least one person and wounded 86, according to the government’s Erawan Emergency Centre, which handles victim counts in crises and disasters. Earlier, Deputy Prime Minister Suthep Thaugsuban had said three had died. It was not immediately possible to reconcile the conflicting accounts.

The attackers shot five M-79 grenades from near where anti-government Red Shirt protesters have been encamped and the blasts struck areas where counter-demonstrators have gathered, but the government stopped short of directly blaming the Red Shirts for the attack.

Thousands of mostly rural Red Shirts have been entrenched on Bangkok’s streets since March 12 in a campaign to dissolve Parliament and hold immediate elections, and Thailand’s powerful military has warned them that time is running out to clear the streets or face a crackdown.

In New York, U.N. Secretary-General Ban Ki-moon voiced concern that the situation could escalate and called for dialogue, his spokesman said. “This is a moment requiring restraint on all sides,” spokesman Martin Nesirky quoted the U.N. chief as saying.

Mr. Suthep urged people who had been demonstrating against the Red Shirts to leave the area for their own safety.

Police and soldiers stood guard at the mouth of Silom Road, the capital’s financial district, while across the intersection, Red Shirts screamed slogans and brandished sharpened bamboo staves. Morning traffic on the normally jammed road was light and fewer workers were seen headed for their offices.

Bangkok’s skytrain service cut its hours of operation and shut down stations in the protest-affected area. A number of stops along the city’s subway routes also were shut down but operating hours remained the same.

The Red Shirts consist mainly of poor rural supporters of former Prime Minister Thaksin Shinawatra and pro-democracy activists who opposed the military coup that ousted him in 2006 after months of demonstrations by the Yellow Shirts.

The Red Shirts believe the government of Prime Minister Abhisit Vejjajiva is illegitimate because it came to power under military pressure through a parliamentary vote after disputed court rulings ousted two elected pro-Thaksin governments. They want Parliament dissolved and new elections held.

The first three blasts happened at about 8 pm at the elevated mass transit skytrain station on Silom Road, which is close to the Patpong entertainment district. Grenades punched two holes in the platform roof, and passengers were rushed away down the station’s stairs by soldiers who were stationed there. At least two people were hurt, though apparently not seriously.

About 30 minutes later two more blasts occurred at an intersection filled with demonstrators protesting against the Red Shirts as well as bystanders. One exploded in front of a sandwich shop near the entrance to a hotel driveway and the other a dozen or so meters down Silom Road in front of a bank.

Chaos ensued, as the scores of wounded were tended to and carried to ambulances. The front window of the sandwich shop was shattered, and a pool of blood was on its stoop.

“The authorities are conducting an investigation, but it’s too soon to give any conclusion,” government spokesman Panitan Wattanayagorn said. “This is the work of the terrorists that the government has always been wanting to get rid off.”

The Army warned on Thursday that time was running out for the Red Shirts to clear the streets, saying soldiers would crack down soon. The protesters are in violation of several laws, including a state of emergency.

“To take people in Bangkok hostage is not right,” Army spokesman Col. Sansern Kaewkamnerd warned. “Your time to leave the area is running out.”

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