The start of the Washington Nationals at St. Louis Cardinals game set for Tuesday night was delayed because of a severe storm that set off a tornado siren.

The Cardinals made an announcement about 20 minutes before the scheduled first pitch that it would not begin on time.

Heavy rain reached Busch Stadium about 20 minutes after the scheduled 7:15 p.m. CST start. Hail came down so hard some small cubes pounded through the roof and into a back aisle of the press box.

Thousands of fans stayed in their seats even after a tornado warning siren sounded, then sprinted up the aisles to relative safety.

Despite the forecast, the grounds crew watered the field right before the storm's anticipated arrival, then rolled out the tarp.

By 9 p.m., with rain still coming down, the temperature had dropped about 20 degrees to 62.