A note addressed to "the people of Chicago and our fans" posted this week on the band's website said that "we still do not have a definitive understanding of what happened and are continuing to investigate this matter."

The note added, "We are not comfortable with the time it is taking us, and we have decided to take action now even though it may turn out the incident was not caused by one of our buses. We simply want to begin the healing process."

To that end, the band wrote that "if we were the responsible party, we offer our deepest apologies to the passengers on the boat, the City of Chicago, or fans and those who have worked so hard to clean up the Chicago River."

The band claims it has contacted the boat owner and tour operator, "and will work with them to identify the passengers that were affected that day and to make things right for all concerned. We know we cannot erase what happened that day, but we hope by reaching out and helping now this will help demonstrate our commitment to step up if we are found to be the responsible party."

In addition, the band has donated $50,000 to the Friends of the Chicago River and the Chicago Park District, and has suspended the driver "who was the only person on the bus during the time in question. The driver continues to steadfastly deny any involvement in the incident."