Jack Wilshere ran the midfield for Arsenal
Arsenal produced a scintillating attacking display to record a first league win of 2013 in emphatic fashion with victory against West Ham.
But an entertaining game was marred by an injury to West Ham's Dan Potts, reports the BBC.
Jack Collison volleyed West Ham ahead but Lukas Podolski equalised from distance as Arsenal took control.
Olivier Giroud poked in and Santi Cazorla's back-heel made it 3-1. Theo Walcott then fired in from a counter before Giroud side-footed home.
There was concern for West Ham towards the end of the second half when 18-year-old substitute Potts needed lengthy treatment on the pitch before he was carried off on a stretcher.
Arsenal remain sixth but cut the gap on fourth-place Tottenham to four points, while West Ham are 12th.
Back in April 2007, West Ham became the first side to beat Arsenal at Emirates Stadium when a solitary Bobby Zamora strike gave them a 1-0 victory.
For a brief spell, it looked as though a repeat of that scoreline might have been on the cards when the Hammers took an 18th-minute lead courtesy of a fine strike by Collison.
A corner was only cleared as far as the edge of the Arsenal area where Collison charged in to smash a half-volley beyond a stranded Wojciech Szczesny.