The death toll from the attack on the Crocus City Hall concert venue in the outskirts of Moscow has risen to 137, authorities said on Sunday according to state news agency TASS. The state Investigative Committee had earlier put the number at 133 but said the death toll was likely to rise as emergency workers continue to search the rubble. More than 150 people were injured when gunmen fired indiscriminately at concert-goers at the packed venue on Friday evening, with many still in critical condition, according to the authorities. Russia observed a national day of mourning on Sunday. The so-call…