Explosions tore through the departure hall of Brussels airport, and a separate blast hit a metro station in the capital shortly afterwards, the Belgian public broadcaster RTBF said.

“Geopolitical risk, including acts of terrorism which directly affect trade or movement, remains a significant risk factor to monitor,” said Lorne Baring, managing director of B Capital Wealth Management in Geneva.”In a period where there is suboptimal growth both in Europe and globally, combined with equity valuations that are no longer cheap, there exists an environment which is susceptible to shocks that can act as a trigger for falls in asset prices.”

The STOXX Europe 600 Travel and Leisure index fell 2.4%, the top sectoral decliner, with shares in easyJet, Ryanair, Accor, TUI and IAG down by 3.1-4.2%.

The pan-European FTSEurofirst 300 index was down 1.1% at 1,324.35 points, while Belgium’s benchmark share index fell nearly 1%. Across Europe, Germany’s DAX fell 1.2%, while France’s CAC dropped 1.3%.

Investors remained focused on unfolding events in Brussels, although there were some positive data releases.

French private sector activity expanded in March at the fastest pace in five months as a stronger than expected rebound in services helped offset weakness in manufacturing, while growth in Germany’s private sector was steady in March, also helped by a solid upturn in the services industry, separate surveys showed.

Bucking the trend, Partners Group shares rose 3.7% after the global private markets investment management firm proposed an increased dividend and said its fiscal year revenues increased by 8% despite foreign exchange headwinds.

Oil prices also fell on Tuesday. It had risen earlier in the session following a drop in U.S. inventory levels that helped ease some of the concern around oversupply that could dampen future price recoveries.

Brent crude futures fell 14 cents to $41.40 a barrel by 0909 GMT, having risen to a session high of $41.75. Brent has gained more than 50% from 12-year lows hit in January.

U.S. May crude futures were down 11 cents at $41.41 a barrel.

“The stocks (fall) in Cushing (U.S. oil delivery hub) helped … but obviously now you have these headlines from Brussels and that can lead to some risk-off positioning. But the movements for now are not very significant,” Petromatrix strategist Olivier Jakob said.

The dollar index and gold, perceived to be less risky options at times of geopolitical or financial uncertainty, rallied in price, while equities and other industrial commodities such as copper came under pressure following the explosions.

The demand for safe-haven assets also prompted top-rated German bond yields to fall to near a two-week low.

The European benchmark yield, which moves inversely to prices, fell 4 basis points to 0.18%, its lowest since March 10. The fall led a broad rally across most of the region’s debt markets after reports of the explosions.

“The tragic events in Brussels have led to a flight-to-quality, which we are seeing in the bond markets,” said Nick Stamenkovic, a bond strategist at RIA Capital Markets.

Hawkish comments from several Federal Reserve policymakers on Monday had been exerting upward pressure on bond yields before the incident as they raise the prospect of further rate hikes in the United States, the world’s largest economy.

Atlanta Fed President Dennis Lockhart said the United States may be in line for a rate hike as soon as April, while Richmond Fed President Jeffrey Lacker said U.S. inflation is likely to accelerate in the coming years and move toward the Fed’s 2% target.

Yields continued to rise slightly when markets opened on Tuesday but then sharply reversed course after reports that of the explosions at the departure hall of Brussels airport and the second blast the a metro station afterwards.

“There was no reason for bonds to open so strongly so you have to assume that it has something to do with this attack in Brussels,” KBC strategist Piet Lammens said.

Analysts said mixed euro zone data was also a factor in falling yields as it supports the need for ongoing monetary stimulus by the European Central Bank.

Private sector growth data in the bloc’s powerhouse Germany was steady in March but the manufacturing component saw its lowest rise in output since November 2014.