Libya's elected congress takes power

• The ceremony marks the first peaceful transition of power in more than 40 years in Libya
• Security issues remain a major concern
• Moammar Gadhafi was ousted and killed last year

Tripoli, Libya (CNN) -- Libya's National Transitional Council handed over power Wednesday to the General National Congress, the national assembly formed by last month's elections.

The ceremony in Tripoli marked the first peaceful government transition in Libya in the more than four decades since Moammar Gadhafi seized power in 1969, and was held on the 20th day of Ramadan, which the NTC chose to mark the anniversary of the start of the liberation of the capital city from Gadhafi's grip.

Security is a major challenge for the country, with militias continuing to operate without government oversight, holding thousands of detainees and carrying out arbitrary detentions.

For example, unknown individuals attacked the residence of the International Committee of the Red Cross in Misrata on Sunday. None of the seven staff members inside the building at the time of the attack was hurt, but the building suffered extensive damage, the ICRC said in a statement.

Sunday's attack marked the fifth in less than three months against the ICRC in Misrata and Benghazi and led Ishfaq Muhamed Khan, the head of the ICRC's delegation in Libya, to suspend operations in those two cities.

In addition, a bomb exploded Saturday in central Tripoli in what officials said was a local dispute.

And last week, a bomb exploded near a security headquarters building in the city of Benghazi. Officials reported defusing two other bombs around that time, including one found in the basement of the Tibesti Hotel, which is frequented by government officials, foreign delegations and nationals.

CNN's Jomana Karadsheh contributed to this report from Tripoli.