Best photography from around the world, April 1

The cliff that collapsed into a massive mudslide is seen covered with felled trees in Oso. Recovery teams struggling through thick mud up to their armpits and heavy downpours at the site of the devastating landslide in Washington state are facing yet another challenge - an unseen and potentially dangerous stew of toxic contaminants. Rick Wilking / Reuters

A Russian tank crew member runs in front of his T-72B tank after their arrival in Crimea in the settlement of Gvardeiskoye near the Crimean city of Simferopol. Yannis Behrakis / Reuters

An Afghan girl holds a mannequin as she looks on in the old part of the northwestern city of Herat. Behrouz Mehri / AFP

An Afghan girl smiles as she looks through a window of her house in the old part of the northwestern city of Herat. Behrouz Mehri / AFP

Supporters of Afghan presidential candidate Zalmai Rassoul attend an election campaign in Bagram. Ahmad Masood / Reuters

Butterflies sit on the face of Isla, aged 6, in the Natural History Museum’s ‘Sensational Butterflies’ outdoor butterfly house in London, England. Oli Scarff / Getty

Shadows of Nobel Prize-winning chemist and President of Japanese research institute RIKEN Ryoji Noyori (L) and a RIKEN executive member are cast on the wall behind Noyori during a news conference in Tokyo. Yuya Shino / Reuters

Malaysia’s acting Transport Minister Hishammuddin speaks during a news conference on the missing Malaysia Airlines Flight MH370 at Putra World Trade Center in Kuala Lumpur. Edgar Su / Reuters

Supporters of Afghan presidential candidate Zalmai Rassoul arrive for an election campaign in Bagram. Ahmad Masood / Reuters