Two Texans suspected of plotting to disrupt the Republican National Convention were charged Friday in federal court with illegally possessing Molotov cocktails.

David Guy McKay, 22, and Bradley Neil Crowder, 23, were each charged with possessing Molotov cocktails. Both remain in custody following initial court appearances in Minneapolis. They have a preliminary hearing on Tuesday.

McKay was arrested by St. Paul police during a search of a home Wednesday. Crowder was arrested Monday on suspicion of disorderly conduct.

According to an FBI affidavit:

The FBI in Texas began investigating a group, labeled by law enforcement as the Austin Affinity Group, in February 2007. Crowder is listed as the group's leader, and McKay has been identified as a member.

On Aug. 28, members of the Austin, Texas, group traveled to Minnesota. The group brought a rental trailer with them that contained 35 shields made from stolen traffic barrels. The shields were constructed with protruding screw heads so that they could be used as offensive weapons. St. Paul police seized the shields Sunday.

McKay and Crowder bought supplies for making Molotov cocktails at a St. Paul Wal-Mart on Sunday. Authorities found that the supplies were stored at a St. Paul apartment and that McKay and Crowder had made eight Molotov cocktails and were storing them at a home on Dayton Street, the affidavit said.

In the search at the Dayton Street residence, where McKay was arrested, officers seized gas masks, slingshots, helmets, knee pads and containers of a gasoline and oil mixture.

In an unrelated incident, a 23-year-old man was charged Friday with assault and terroristic threats for allegedly dropping a 50-pound bag of sand onto Interstate 94 on the first day of the Republican National Convention.

David Terence Mahoney, no permanent address, was arrested Thursday in Minneapolis. He made his first appearance Friday, and his bail was set at $25,000 in Ramsey County District Court.

In a criminal complaint filed by the Ramsey County attorney's office, authorities allege that Mahoney picked up the bag of sand holding down a traffic sign and tossed it off the John Ireland bridge over I-94 Monday afternoon while he and a group of about 50 protesters marched in the area.

Investigators were able to identify Mahoney through a tattoo on his back, noticeable on surveillance photographs that authorities took when the sandbag was tossed.

The bridge went over one of the primary routes that convention delegates and their buses used to get to the Xcel Energy Center.

hme@startribune.com • 612-673-4280 pwalsh@startribune.com • 612-673-4482