At least seven people were killed and more than a dozen others were injured when a car bomb exploded on the Syria side of the rebel-held Bab al-Hawa border crossing with Turkey.
The International News Safety Institute, which has headquarters in London, said journalists working along the border were advised to "exercise extreme caution" because of reports of kidnapping and violence.
"The perpetrators of this most recent attack are unknown," ISNI said in an advisory Thursday. "However, Syria-based armed groups are believed to have previously carried out attacks in this area. "
Turkey's English-language newspaper Today's Zaman reported this week the Turkish military said it stopped thousands of smugglers from crossing into the country from Syria.
INSI said more than 50 people were killed in a bombing near Bab al-Hawa in May. It called on journalists working in the region, or inside Syria itself, to work only with vetted and trusted local sources.
"INSI urges journalists to undertake hostile environment and medical training prior to taking any assignment in Syria," it said. "They should ensure that they have carried out a thorough risk assessment and have robust contingency plans, including a confirmed communications plan."
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