During Monday's attack, the police officer manned a heavy machine gun mounted in the back of one of the ANP vehicles and began firing on U.S. and Afghan forces. Four other ANP officers were wounded, including the police chief for Jalrez, before the attacker was gunned down.
Five ANP officers purportedly involved in planning the attack in have been detained by U.S. and Afghan forces for questioning, provincial Deputy Police Chief Abdul Razaq Koraishi told the AP on Monday.
Wardak has recently become a flashpoint for growing tensions between Washington and Kabul, as American and NATO commanders prepare for the final withdrawal from the country next year.
In February, Afghan president Hamid Karzai ordered all U.S. special forces units out of Wardak, amid accusations of abuse, torture and murder of Afghan civilians at the hands of American troops.
The Pentagon has denied the accusations against U.S. special forces, but a joint inquiry led by Gen. Joseph Dunford, the top U.S. commander in Afghanistan, into the allegations is still ongoing.
Monday's attack comes a day after Hagel wrapped up his first visit in country on Sunday.
On Saturday, Taliban fighters detonated a bicycle bomb outside the Ministry of Defense headquarters in Kabul where Hagel was meeting with top officials from the Afghan National Security Forces (ANSF).
The group claimed responsibility for the attack, which killed over 18 Afghans and wounded dozens more, as a "message" to Hagel and Washington as the U.S. and its allies attempt to bring the over decade-long war to an end.
On Sunday, Dunford told reporters the recent unrest in Wardak and elsewhere were symptomatic of the transition pains that accompany the ongoing U.S. pullout plan in Afghanistan.
"There are transitions happening all over Afghanistan," Dunford told reporters on Monday. "Some areas are more ready for transition than others."
That said, "Wardak is going to transition to Afghan National Security Forces," the four-star general added. "The only issue is the timeline and the methodology and we're still working on that."
Aside from Wardak, anti-American accusations coming from the Karzai government have become more belligerent in recent weeks.
On Saturday, Karzai accused Washington of secretly collaborating with Taliban forces in an attempt to destabilize the central government's hold on power in the run up to the 2014 U.S. drawdown.
For his part, Dunford dismissed Karzai's claims, noting the United States has "fought too hard" in Afghanistan to simply negotiate control of the country to the Taliban.
“We have fought too hard over the past 12 years. We have shed too much blood over the past 12 years . . . to ever think that violence or instability would be to our advantage,” Dunford said.
However, some on Capitol Hill are concerned Karzai's recent statements and edicts restricting American operations in the run up to the 2014 withdrawal could place U.S. and allied forces at risk.
Sensing the end is near, local and national leaders are doing all they can to solidify their power bases across Afghanistan, Rep. Mac Thornberry (R-Texas) told The Hill last month.
That pressure could force Afghan leaders -- particularly at the provincial and district level -- to forge alliances with the Taliban rather than the central government, to fill the power vacuum left after 2014, Thornberry, who chairs the House Armed Services emerging threats and intelligence subcommittee, said.
While Karzai's recent could make the U.S. withdrawal difficult, they are not unexpected, Dunford said.
"These [are] issues that have to be addressed are a natural tension as Afghanistan increasingly asserts its sovereignty. These should be expected," Dunford said. "But they do not at all characterize the relationship that we have with" the ANSF or the Karzai administration.