More than 300 pounds (135 kilograms) of cocaine valued at more than $10 million (euro7.74 million) were found hidden in the support beams of a flatbed trailer hauling cinder blocks from Mexico, authorities said Monday.

A drug-sniffing dog caught the scent of cocaine, and customs officers using an X-ray scanner noticed odd shapes near the beams of the trailer Friday at the Pharr international bridge. The officers discovered 121 bricklike packages of cocaine hidden in a space between the support beams and the floor of the trailer.

Felix Garza, a spokesman with Customs and Border Protection, would not comment on whether arrests were made. The Mexican-registered truck and trailer were seized.