Blast kills two, wounds 11 in east Ukraine city.
The explosion happened during a pro-Ukrainian march marking the one-year anniversary of the overthrow of the country's former pro-Kremlin president.
Regional prosecutor Yuri Danilchenko said two people died, one of them a police officer, revising down an earlier toll of three killed.
"It was a homemade bomb packed with shrapnel, put in a plastic bag and hidden in snow by the side of the road," he told reporters.
An AFP reporter saw the two bodies lying on the ground covered with Ukrainian flags.
A Ukrainian security service adviser, Markian Lubkivksi, said on his Facebook page that "people who might have been involved" in the attack had been arrested, without elaborating.
Kharkiv is located more than 200 kilometres (120 miles) from the frontline where pro-Russian rebels are fighting government forces.
Other marches celebrating the overthrow of former president Viktor Yanukovych a year ago, after street protests brutally repressed by snipers, were taking place in Kiev and other parts of Ukraine on Sunday.
A UN-backed ceasefire came into effect in Ukraine's east a week ago but has been largely ignored by both sides in the conflict.
-AFP