Scientists at the CERN laboratory in Geneva may have been glimpsed the most coveted prize in particle physics - the Higgs boson.
The particle is thought to be the means by which everything in the Universe obtains its mass.
Scientists have been searching for it in experiments using the Large Hadron Collider, a device that accelerates particles to huge speeds in a tunnel beneath the Swiss-French border.
The BBC reports two experiments at the LHC have seen hints of the Higgs at the same mass, fuelling huge excitement. But the LHC does not yet have enough data to claim a discovery.
The BBC's science editor says that finding the Higgs would be one of the biggest scientific advances of the last 60 years. It is crucial for allowing us to make sense of the Universe, but has never been observed by experiments.
Two separate experiments at the LHC - Atlas and CMS (Compact Muon Solenoid) - have been conducting independent searches for the Higgs.
Because the standard model does not predict an exact mass for the Higgs, physicists have to use particle accelerators like the LHC to systematically look for it across a broad search area.
At a seminar at the CERN laboratory on Tuesday, the heads of Atlas and CMS said they see "spikes" in their data at roughly the same mass: 124-125 gigaelectronvolts (GeV).
CERN director-general Rolf-Dieter Heuer told BBC News: "Such signals can come and go … Although there is correspondence between the two experiments, we need more solid numbers."
None of the spikes seen by the experiments is at much more than the "two sigma" level of certainty.
"We can be misled by small numbers, so we need more statistics," said Professor Heuer, but he added: "It is exciting."