A firefighter suffered minor injuries in a warehouse fire Sunday morning. Denver Fire posted just before 8 a.m. that crews were working a commercial structure fire near the intersection of 40th and Walnut streets involving a vacant warehouse showing heavy smoke and fire. At 8:45 a.m., the department said the fire was upgraded to a second alarm due to the volume of flames and potential collapse hazard, forcing crews to initially back out and attack the fire from the exterior. Read more at: https://www.9news.com/article/news/local/firefighter-injured-fighting-warehouse-fire/73-808fdce7-05ba-4340-abbc-ce3bf56e90a2 More local videos here: https://youtube.com/@9news Subscribe to NEXT: https://youtube.com/@Nexton9NEWS Stay connected: 9NEWS Website: https://www.9news.com/ Facebook: https://www.facebook.com/ilike9news Twitter: https://twitter.com/9NEWS Instagram: https://www.instagram.com/9newsdenver/ Download the 9NEWS App: https://www.9news.com/appredirect/ Sign up for the 9NEWSLETTER: https://www.9news.com/email 9NEWS (KUSA) is located in Denver, Colorado.