A Customs and Border Patrol (CBP) unit at the scene of the Uvalde, Texas, elementary school shooting was told not to enter the school and instead wait, according to a report from NBC News.

Two federal officials who spoke to the outlet said that agents who were part of BORTAC, CBP’s tactical unit, arrived on the scene at Robb Elementary School around 12:15 p.m., approximately 45 minutes after the suspected shooter began his rampage.

ICE Homeland Security Investigations division was also on the scene, according NBC.

Once there, local police asked them to wait and assist pulling students out of windows. However, after 30 minutes passed, the federal agents decided to move in on the shooter and take him out.