Updated at 09:55 ET: Hamas said on Thursday that one of its members, Kamal Husni Ghanaja, had been killed in his home in Damascus and that it was trying to find who was behind what the Palestinian Islamist group described as a "cowardly murder."
Hamas, which rules the Gaza Strip, said in a statement that it was trying "to identify the party behind the deplorable crime," but did not immediately accuse Israel, its long-time enemy, of involvement in the killing.
ISKENDERUN, Turkey -- Turkish troops and military vehicles deployed toward the border with Syria on Thursday as a precaution after Prime Minister Tayyip Erdogan gave orders to react to any Syrian threat approaching the frontier.
Erdogan, who has given shelter in the border area to rebels fighting Syrian President Bashar Assad, announced the new rules of engagement for Turkish troops on the border after Syrian air defenses shot down a Turkish warplane last Friday.
"I can confirm there are troops being deployed along the border in Hatay province. Turkey is taking precautions after its jet was shot down," a Turkish official said on condition of anonymity.
He said he did not know how many troops or vehicles were being moved but said they were being stationed in the Yayladagi, Altinozu and Reyhanli border areas of Turkey's southern Hatay province. He said anti-aircraft guns were also being stationed along the border.
A military convoy of vehicles including anti-aircraft missile launchers from the 5th Mechanized Armored Brigade left a base in the southeastern city of Gaziantep on Thursday and travelled to neighboring Kilis province on the border, video from the Turkish Dogan news agency showed.
Roads were closed to traffic as the convoy, escorted by police cars, passed by.
Another convoy of about 30 military vehicles, including trucks loaded with missile batteries, left Turkey's coastal town of Iskenderun on Wednesday and deployed near the Syrian border 30 miles away, Turkish news agencies said.
Turkish television film showed the column moving on Wednesday, escorted by police cars, along a narrow highway leading out of the town, the main port of Turkey's Hatay province. It included rocket launchers on transporters, anti-aircraft artillery and military ambulances.
A Reuters journalist saw another large truck carrying an anti-aircraft gun leave Iskenderun on Thursday for the border area, escorted by two army trucks, one carrying 10 troops.
'No more tolerance'
Erdogan said any military element moving towards the Turkish border and deemed threatening would be declared a military target. The preponderance of air defense weapons in the convoy suggested Turkey was preparing for any possible approach by Syrian helicopters or warplanes.
While the military movements were ratcheting up the pressure on Syria, Turkey was likely being very careful, NBC News producer Aziz Akyavas in Turkey said.
"Syria has been chasing Syrians fleeing the country and hitting Turkish soldiers and posts," he said on the telephone on the border with Syria. "Turkey is saying, from now on no more tolerance."
The Turkish border region is sheltering more than 33,000 Syrian refugees as well as elements of the rebel Free Syrian Army.
But "the Turks are being very careful, using diplomatic language very carefully -- a war would be a real disaster," he added.
State-run Anatolia news agency said armored military vehicles were being transported to military installations in Sanliurfa, in the middle of Turkey's border with Syria, and Hatay, a panhandle province that juts down into Syria.
It said several military vehicles had travelled separately to a military garrison in the border town of Reyhanli in Hatay.
Specific details have not been made public of the new rules of engagement issued to troops after the shooting down of the warplane, which Turkey says was in international air space but Syria says entered its territory at high speed.
Aram Nerguizian, a Syria expert at Washington, D.C.,-based think tank Center for Strategic and International Studies, told msnbc.com that Assad "has a very small window" to say that the downing of the the Turkish fighter was a mistake.
"Syria is sitting and not providing a high-level response to this (and) the last thing these players should be doing is not talking to each other," he said. "These are two of the region’s largest militaries and it would be disastrous if things deteriorated in ways neither side expected."
Nerguizian added that "neither side wants to show weakness."
Blast near busy market
Meanwhile, a strong explosion rocked the Syrian capital Thursday near a busy market and the Palace of Justice, sending black smoke billowing into the sky. State TV reported at least three people were wounded and around 20 cars were damaged.
An Associated Press reporter at the scene said some cars were charred and many had their windshields blown out.
Syria's state-run TV said the explosion was in the parking lot of the Palace of Justice, a compound that houses several courts. The blast happened at 1 p.m. 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 two explosions struck the area. The report also said a roadside bomb was found but did not explode.
Msnbc.com's F. Brinley Bruton, NBC News' Aziz Akyavas, Reuters and The Associated Press contributed to this report.
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