Providence police have issued an arrest warrant for the suspect in the Brown University mass shooting that left two students dead and nine injured, sources told CBS News. Authorities are searching in Salem, New Hampshire, where law enforcement presence is heavy. Police found an abandoned rental car linked to the suspect near a storage facility. The suspect's identity has not been made public. Armed officers were seen on NBC Boston footage aiming guns at buildings in Salem. Investigators are checking if there is a connection between the Brown University shooting and the murder of Nuno F Gomes Loureiro, a MIT nuclear science professor, who was shot multiple times two days later in Brookline, Massachusetts. The search has lasted six days, with police canvassing homes, collecting security footage, and asking the public for tips. Providence police canceled a planned news conference but said updates will come later. Sources revealed that the same rental car was spotted at both crime scenes. Federal officials had earlier denied any connection between the murders. On Wednesday, police released a photo of a person possibly linked to the main suspect. Providence Police Chief Oscar Perez said, "we want to speak with the person, who may have information relevant to the investigation." He added, "the killer could be anywhere". Previously, police showed video of a masked individual reportedly scouting Brown University before the attack. Public frustration over the slow progress of the case is growing, but Rhode Island Attorney General Peter Neronha stated he believes the suspect will be caught soon. The FBI has announced a $50,000 reward for information leading to the arrest and conviction of the shooter. The shooting happened inside Brown's Barus & Holley engineering building during final exams. The two students killed were Ella Cook, a sophomore from Alabama, and Mukhammad Aziz Umurzokov, an Uzbek-American freshman.