KABUL, Afghanistan — Taliban-led insurgents opened a spring offensive Sunday with a wave of coordinated suicide missions, firing at embassies and government offices from seized buildings in Kabul and attacking U.S. bases and police stations in three eastern provinces.

The strikes, which seemed to catch U.S.-led forces and Afghan authorities by surprise, sparked fierce firefights in Kabul and two other cities that underscored the insurgency's lethality as U.S. combat troops gird for the second phase of a withdrawal due to end in 2014.

"This is the start of the spring operations," Zabihullah Mujahid, a Taliban spokesman, declared in a cellphone interview with McClatchy. "This is just the beginning."

The violence, which lasted past nightfall in Kabul and Puli Alam, the capital of neighboring Logar province, claimed the lives of at least 26 insurgents and four civilians, Afghan and NATO officials said. At least 36 others, mostly civilians, were wounded. All of the casualties were Afghans. Some of the attackers were captured.