By Carlos Barria and Mehmet Emin Caliskan IRPIN, Ukraine (Reuters) -Ukrainians fleeing the town of Irpin just outside Kyiv were caught in shelling by Russian forces on Sunday and forced to dive for cover, Reuters witnesses said. Irpin, some 25 km (16 miles) northwest of the capital, has seen intense fighting in recent days. Russia’s military is closing in on Kyiv, home to around 3.4 million people before the invasion sparked a mass exodus of civilians. Irpin residents scurried along pavements clutching children, luggage and pets as they made their way to waiting buses and cars that would take …