Forces loyal to a rogue Libyan general attacked the country's parliament Sunday, expanding his eastern offensive against Islamists into the heart of the country's capital. Gunmen detained some 20 lawmakers and officials, authorities said, as black smoke rose over the parliament.

The violence, three years after the 2011 civil war that toppled dictator Moammar Gadhafi, threatens to further splinter a country dominated by militias.

The troops of Gen. Khalifa Hifter targeted Islamist lawmakers and officials, his spokesman Mohammed al-Hegazi told Libya's al-Ahrar television station.

Al-Hegazi said Hifter blames the officials for allowing extremists forces to exert considerable influence in the country.

His troops struck two Islamists militia bases Friday in Benghazi, the country's second-largest city, setting off clashes that killed 70 people, Libya's Health Ministry said.

"This parliament is what supports these extremist Islamist entities," al-Hegazi told the station. "The aim was to arrest these Islamist bodies who wear the cloak of politics."

Al-Hegazi said Hifter's forces met resistance from militias he accused of "holding the country hostage." He called the parliament the "heart of the crisis" in Libya.

The head of the parliament, the Islamist-leaning Nouri Abu Sahmein, later told TV station al-Nabaa that the militias loyal to the parliament and government have matters "under control."

"Those who plan and plot such things want to strike here and there to make others feel he has influence," Abu Sahmein said. "We are not in battle with individuals. We are carrying out a role that we were elected to do."

Gunfire near parliament could be heard for kilometers (miles) around. Witnesses said the attacking forces shelled parliament from the city's southern edge. The attackers rode in on trucks mounted with anti-aircraft guns and armored vehicles.

Lawmaker Khaled al-Mashri told Libya's al-Ahrar television station that gunmen entered the parliament complex, damaged the building and attempted to detain employees and guards.

An official with the Libyan Revolution Operation Room, an umbrella group of militias groups who answer to the interim parliament and are in charge of the security in the capital, said fighters engaged the attackers but there were no reports of casualties. He said the attackers also "kidnapped" some 20 lawmakers and government officials. Gunfire could be heard on the road to Tripoli's airport and fire continued after sunset.

The official spoke on condition of anonymity because he was not authorized to brief journalists.

Forces loyal to the interim parliament set up checkpoints around the parliament, sending journalists away.

The spokesman said the attacking forces are suspected members of the al-Qaaqaa and Sawaaq militias, the largest in the capital. While they operate under a government mandate, they back the non-Islamist political forces.

Al-Qaaqaa posted a statement on its official Facebook page, saying it attacked parliament with Sawaaq because lawmakers supported "terrorism."

The two groups previously gave parliament an ultimatum to dissolve after its mandate expired in February, threatening to detain lawmakers. They never carried out their threats, though the parliament vowed to hold elections later this year.

Lawmakers say security officials evacuated them from the building out of fears it would be stormed. The security official told The Associated Press that lawmakers received warnings ahead of the attack that the building would be assaulted.

Libya's parliament is divided between Islamist and non-Islamist. Rival militias, which wield the real power in Libya, have lined up behind competing political factions.

Recently, Islamists backed the naming of a new prime minister amid walkouts from the non-Islamist groups. The new interim prime minister has not yet named a Cabinet.

Al-Mashri said the attackers wanted to prevent lawmakers from picking a new Cabinet.

"There aim is to destroy an icon democracy elected by the people," he said.

But splits in Libya are also regional and ethnic, with longstanding rivalries between the country's eastern and western regions.

Since Hifter's offensive in Benghazi began on Friday, many of his supporters have pushed for him to take action in the capital, Tripoli, complaining about the country's ineffective government.

On Saturday, Hifter said he will press on with his offensive in Benghazi, despite warnings by the central government that cooperating troops will be tried. They labelled his moves a coup attempt.

Hifter, who once headed the army under Gadhafi but defected in the 1980s, had been assigned to help rebuild the country's military, but he was removed soon after. He appeared in an online video in February and proclaimed he intended to "rescue" the nation. Authorities described also that declaration as a coup attempt, though he apparently was never arrested.