BENGHAZI, Libya (CNN) - Four people have been arrested in connection with the attack on the U.S. consulate in Benghazi that left U.S. Ambassador to Libya J. Christopher Stevens and three other Americans dead, the Libyan prime minister's tope aide said Friday.
Those arrested were not directly tied to the attacks that resulted in the deaths, Monem Elyasser, the chief aide to Prime Minister Mustafa Abushagur, told CNN by telephone.
The announcement came as the United States is struggling to determine whether a militant group planned the attack that killed the four Americans.
Elyasser did not release the identities of the suspects nor did he detail the allegations against the four people in custody.
During an interview on CNNI's "Amanpour," Abushagur said Thursday that there had been one arrest early Thursday in Benghazi and three or four others who were being pursed.
"The evidence itself is based on mostly pictures that were taken around the compound at that time, and also through some witnesses," he said.
Conflicting theories flew in the hours after Stevens, another diplomat and two State Department security officers were killed late Tuesday in the eastern city of Benghazi.
They died amid a protest outside the U.S. consulate over a film that ridiculed Muslims and depicted the Prophet Mohammed as a child molester, womanizer and ruthless killer.
"I think the degree to which we're able to update this information or deepen it, it's going to be in the context of beginning to interview our employees who are coming out and beginning to participate in the investigation that the Libyans are doing," U.S. State Department spokeswoman Victoria Nuland told reporters Thursday.
The demonstration was one of several protests across the region that day.
Protest as diversion
U.S. officials believe the attackers used the protest as a diversion.
Given what officials know about al Qaeda in Libya, intelligence officials believe it is very unlikely that core al Qaeda was behind the attack, a U.S. intelligence official told CNN on condition of anonymity. The official was not authorized to release the information.
State Department Under Secretary Patrick Kennedy has said that the attack appeared to be planned because it was so extensive and because of the "proliferation" of small and medium weapons at the scene. He was briefing congressional staffers when he offered that theory.
But on Thursday, three U.S. officials told CNN that they have seen no evidence the attack was premeditated.
Meanwhile, Shawn Turner, director of communications for U.S. National Intelligence, denied news reports that American officials had been warned of a possible attack.
"This is absolutely wrong," he said. "We are not aware of any actionable intelligence indicating that an attack on the U.S. post in Benghazi was planned or imminent."
The United States is deploying warships and surveillance drones in its hunt for the killers of the diplomatic staffers, and a contingent of 50 Marines has arrived to boost the security of Americans in the country.
The United States and Libya have embarked on a new relationship since rebels toppled longtime dictator Moammar Gadhafi last year.
U.S. and NATO warplanes helped the Benghazi-based rebellion against Gadhafi, who was wanted by the International Criminal Court for charges of crimes against humanity before the ruler was killed in October.
The jihadists suspected in Tuesday night's attack "are a very small minority" who are taking advantage of a fledgling democracy, said Ali Suleiman Aujali, the Libyan ambassador to the United States.
Sources tracking militant Islamist groups in eastern Libya say a pro-al Qaeda group responsible for a previous armed assault on the Benghazi consulate is the chief suspect. A senior defense official told CNN the drones would be part of "a stepped-up, more focused search" for a particular insurgent cell that may have been behind the killings.
Questions swirl around the attack
There are numerous questions about what happened at the consulate where protesters had gathered to demonstrate against the film "Innocence of Muslims," which reportedly was made in California by a filmmaker whose identity is unclear.
Chief among the questions is what happened to Stevens, who went missing during the attack.
What is known is that during the attack, a rocket-propelled grenade set the consulate on fire, and American and Libyan security personnel tried to fight the attackers and the fire.
As the fire spread, three people -- Stevens, Foreign Service information management officer Sean Smith, and a U.S. regional security officer -- were inside a safe room, senior State Department officials, who spoke on condition of anonymity as a matter of practice during a briefing with reporters.
Smith was later found dead, apparently of smoke inhalation, officials said.
The State Department has not released details about how Stevens died, though numerous media reports have said the ambassador was taken from the consulate to the