(CNN) - Candidates in this month's primaries for the special U.S. Senate election in Massachusetts announced they were suspending campaign activity Monday as authorities continue to investigate apparent bombings at the Boston Marathon.
Rep. Ed Markey, the Democratic frontrunner, said he was "disturbed and saddened" by the explosions that left dozens injured and caused multiple deaths.
"We all are grateful for the first responders who rushed to the scene to help the victims. The heart of the city is hanging heavy, and our thoughts and prayers are with everyone affected by this senseless tragedy," the longtime congressman, who represents Boston suburbs, said in a statement.
Republican businessman Gabriel Gomez has also suspended campaign activities. A spokesman confirmed Gomez was running the marathon and finished just before the bomb went off but was not injured. The candidate had planned to hold a press conference after the race.
Two other Republicans vying for the nomination–Michael Sullivan, a conservative former U.S. attorney, and Daniel Winslow, a state lawmaker–also announced they would break from campaigning.
"While the causes of these explosions have not yet been determined, if not accidental, I know these agencies and others will identify those responsible for these horrific and cowardly acts of violence and hold them accountable to the fullest extent of the law," Sullivan said in a statement. "May we together as citizens of the Commonwealth and across this nation pray for all effected by this terrible event."
Another Democratic candidate, Rep. Stephen Lynch, will also suspend campaign activity.
Spokesman Conor Yunits said the congressman, who represents a large part of Boston, was in the city but wasn't at the marathon. They had a staffer who was running the race but got word that she is OK.
The Republican and Democratic primaries are set for April 30, while the special election is scheduled to occur in June. The seat was left open when John Kerry became Secretary of State earlier this year.
Democratic Gov. Deval Patrick appointed his former chief of staff, William "Mo" Cowan, to serve as interim senator until the special election in June.
- CNN's Paul Steinhauser, Mark Preston, Deirdre Walsh and Ashley Killough contributed to this report.