KABUL (AP) ― A brazen, 18-hour Taliban attack on the Afghan capital ended early Monday when insurgents who had holed up overnight in two buildings were overcome by heavy gunfire from Afghan-led forces and pre-dawn air assaults from U.S.-led coalition helicopters.

Kabul residents awoke Monday to a second day of loud explosions and the crackle of gunfire. As darkness turned to dawn, Afghan-led forces fired one rocket-propelled grenade after another into a building in the center of the city where insurgents began their attack Sunday.

Fighting there and at the Afghan parliament building on the southwest side of the city ended just before 8 a.m.

Authorities said one police officer and at least 17 militants were killed in the multi-pronged attacks in Kabul and three eastern cities. The violence showed the Taliban and their allies are far from beaten and underscored the security challenge facing government forces as U.S. and NATO forces draw down. The majority of international combat troops are scheduled to leave by the end of 2014.

The Taliban began their near-simultaneous assaults on embassies, government buildings and NATO bases at 1:30 p.m. Sunday, saying it was their response to NATO officials’ recent claims that the insurgency was weak.

The U.S., German and British embassies and some coalition and Afghan government buildings took direct and indirect fire, according to Lt. Col. Jimmie Cummings, a spokesman for the U.S.-led coalition.

Local residents near the parliament building said rocket-propelled grenades and gunfire rocked their neighborhood through the night and into the morning.

Afghan Interior Ministry spokesman Sediq Sediqi said militants took up position in a building under construction near parliament. Some lawmakers grabbed weapons and started fighting when militants fired on the parliament building on Sunday.

Reporters for the Associated Press witnessed the Monday morning assault on another building under construction near the presidential palace, western embassies and Afghan ministries.

Shortly before 3 a.m., coalition helicopters began flying over the building. At 4:23 a.m. a religious cleric began calling Muslim worshippers to prayer over a loudspeaker in the area. During the next 15 minutes, troops launched five rocket-propelled grenades into the building. More followed.

The loud booms from the blasts momentarily silenced chirping birds. Red and white flashes could be seen inside the various floors of the multistory building. By about 6:30 a.m., the blasts and shooting had stopped.

An intelligence official, speaking on condition of anonymity because he was not authorized to speak to the news media, said an operation to clear the building was nearly completed. The official said one insurgent was still defending the building, but that at least four other militants had been killed.

The first explosions on Sunday rocked the diplomatic quarter of Kabul.

Soon gunshots and rocket-propelled grenade fire were ringing out across the city. Smoke rose over the skyline as sirens wailed. A loudspeaker at the U.S. Embassy could be heard barking: “Duck and cover. Move away from the windows.”

It was the most widespread attack in the Afghan capital since an assault on the U.S. Embassy and NATO headquarters last September blamed on the Haqqani network, a Pakistan-based insurgent group allied with the Taliban. Explosions and the crackle of gunfire could be heard throughout the night.

The sophistication and firepower of the latest strikes, as well as the high-profile government and foreign targets, bore the hallmarks of the attack last fall and others carried out by Haqqani insurgents.

As in the earlier attack, armed insurgents took over half-built buildings Sunday and used them to fire down on nearby embassies and bases. In the streets of Kabul’s Wazir Akbar Khan neighborhood, where a NATO base and a number of embassies, including the U.S. Embassy, are located, residents scrambled for cover as gunfire rained down from all directions.

“I saw two Land Cruisers pull up and two militants jumped from the car,” said Mohammad Zakar, a 27-year-old mechanic who has a shop near the building commandeered by the militants. “They opened fire on an intelligence service guard ... They also fired and killed an Afghan policeman and then they jumped into the building. All the shops closed. I ran away.”

Militants also attacked a NATO site on the outskirts of Kabul, where a joint Greek-Turkish base came under heavy fire and forces responded with heavy-caliber machine guns, according to an AP reporter at the scene. A police officer said a suicide bomber inside a building near the base was shooting toward the Kabul Military Training Center.

The eastern cities of Jalalabad, Gardez and Pul-e-Alam also came under attack, with suicide bombers trying to storm a NATO base, an airport and police installations.

Taliban spokesman Zabiullah Mujahid said dozens of suicide attackers and gunmen were involved in attacks that had been planned for two months to show the insurgency’s power after NATO commanders called the Taliban weak and said there was no indication they were planning a spring offensive.

“We are strong and we can attack anywhere we want,” Mujahid said, calling the attacks an opening salvo ahead of the yearly spring offensive, when warmer weather typically brings increased attacks.

The near-simultaneous assaults were the latest blow to an international effort that has been on edge for months. Distrust between international and Afghan forces has grown following the release of a video purporting to show Marines urinating on Taliban corpses, as well as the burning of Qurans at a U.S. base and a deadly attack by a U.S. soldier that killed 17 Afghan villagers.