BEIRUT — Turkey deployed anti-aircraft guns, rocket launchers and other weapons along its border with Syria on Thursday.

Also on Thursday, a bomb exploded in central Damascus near a busy market and the country’s main justice complex, wounding at least three people, damaging cars in a parking lot and sending a black cloud rising above the Syrian capital.

It was not clear who was behind the bombing.

A small convoy of Turkish military trucks towing anti-aircraft guns entered a military outpost in the border village of Guvecci, which faces a Syrian military outpost, according to TRT television video.

Several anti-aircraft guns also have been deployed elsewhere along the border. Some trucks were seen carrying self-propelled multiple rocket launchers, the video showed.

Syria insists the Turkish military plane it shot down on June 22 had violated its airspace. Turkey says the jet had unintentionally strayed into Syria’s airspace and was inside international airspace when it was brought down over the Mediterranean by Syria.

The search for two missing pilots continued in Syrian waters but hopes for their survival are dim, Turkish authorities said. The Turkish military said search teams have found some pieces of the plane as well as equipment belonging to the pilots.

Syria’s state-run TV said the bombing occurred at 1:00pm in the parking lot of the Palace of Justice, a compound that houses several courts.

The site is near the capital’s famous Hamidiyeh Market, an area crowded with families stocking up on food and other supplies for the weekend, which begins on Friday in Syria.

Witnesses reported hearing one blast, but state-run TV said there were two. The report also said a roadside bomb was found but did not explode.

An AP reporter at the scene said some cars were charred and many had windshields blown out.

“I did not see any wounded people, but cars and nearby shops were damaged,” said Fawaz Mishhim, who was in a nearby market when he heard the explosion.

The government blamed the attack on terrorists, the term it uses to describe rebels. Syria prevents journalists from working independently, making it difficult to verify accounts from either side in the conflict.

The country has been hit by a wave of explosions in recent months, killing dozens of people. Most targeted government security agencies.

Last month, an explosion targeted a military intelligence compound south of Damascus, killing 55 people. It was Syria’s deadliest blast.

US State Department spokesperson Victoria Nuland condemned the latest bombing in Syria. She said that “the longer [President Bashar] Assad continues on his current course, the longer he perpetrates violence against his own people, he creates the conditions for this kind of loss of control, including in the capital.”

Also Thursday, Syria’s state-run news agency, SANA, said terrorists assassinated a professor at the Petrochemical Engineering College at Al Baath University in the central province of Homs, along with five of her relatives.