Ankara, Rajab 4, 1434, May 14, 2013, SPA - Turkey's prime minister says authorities have detained four more people in connection with two car bomb attacks in a Turkish town near the Syrian border, bringing the number of suspects in custody to 13. Prime Minister Recep Tayyip Erdogan also says Tuesday the death toll in the attacks has increased to 51. Erdogan reiterated that Turkey would act in a "cool-headed" manner although it was "powerful, determined and experienced enough to make the culprits pay" for the attacks. He said investigators are also probing possible security negligence by authorities, according to a report of the Associated Press. --SPA 14:27 LOCAL TIME 11:27 GMT www.spa.gov.sa/1110178