BUENOS AIRES, Argentina (AP) _ A train packed with morning commuters slammed into a downtown station on Wednesday, killing 49 people and injuring hundreds as passenger cars crumpled and windows exploded around them. It was Argentina's worst train accident in decades.

The cause wasn't immediately determined, but many pointed to a deteriorating rail system. Some passengers reported signs the conductor was struggling with the brakes before the crash, saying he kept overshooting platforms and missed one entirely.

The dead included 48 adults and one child _ most of whom had crowded into the first two cars to get ahead of the rush-hour crowds on arrival. Some 600 people were injured, including 461 who were hospitalized, Transportation Secretary J.P. Schiavi said.

Hours after the crash, passengers' relatives gathered at the morgue anxious for word of their loved ones.

Ezekiel Mercado said he and his mother-in-law had been frantically searching for his wife, Sabrina Espindola, 29, who didn't show up for work Wednesday. They checked nine hospitals before heading to the morgue, he said.

``I went everywhere. She is always with her Blackberry. We are always in contact,'' he said. ``This morgue is the last place I thought of, but, well, she's missing. I call her cell phone, and it rings, rings, but she isn't responding.''

Speaking at a news conference, Schiavi defended the rail system's maintenance record.

``It was an accident like those in many other countries,'' he said, pointing to a newspaper clipping about a fatal crash in Los Angeles. ``In recent years, we've made huge investments'' in the system.

As Schiavi spoke, riot police faced off against angry passengers in the closed Once station, where emergency workers spent hours extracting dozens of people trapped inside the train's first car. Rescuers had to slice open the roof and set up a pulley system to ease them out one by one. Dozens of the injured were lined up on stretchers on the station platform.

The 28-year-old conductor, who survived the crash, was apparently well-rested, Schiavi said, having just begun his workday.

``Tiredness, his (young) age, the problems that a conductor might face'' are among the factors being investigated, he said. ``This young person had just begun his shift moments before the accident.''

The motorman was hospitalized in intensive care and hasn't given a statement, Schiavi added.

Passengers said the conductor seemed to struggle with the brakes, missing his stopping marks at station after station, though a labor union official said the train appeared to be in good working order.

``This machine left the shop yesterday and the brakes worked well. From what we know, it braked without problems at previous stations. At this point I don't want to speculate about the causes,'' union chief Ruben Sobrero told Radio La Red.

Schiavi said the train was recorded slowing from about 30 miles per hour (50 kph) to 12 miles per hour about 40 yards (meters) before the impact. ``We don't know what happened in those final 40 meters,'' he said.

The train slammed into a shock-absorbing barrier at 8:33 a.m., smashing the front of the engine and crunching the much lighter cars behind it. The second car penetrated nearly 20 feet (six meters) into the next, Schiavi said.

Most damaged was the first car, where passengers shared space with bicycles. Survivors said many people were injured in a jumble of metal and glass. Security camera images showed windows exploding as the cars crumpled into each other like an accordion, with a man on the adjacent platform scrambling across the tracks to escape the wreck.

The rush-hour train carried more than 1,200 people, many standing so tightly between the seats that they had nothing to hold onto. The hard stop sent them flying inside the cars.

Many suffered bruises or lesser injuries, waiting for attention on the station's platforms as helicopters and dozens of ambulances carried others to nearby hospitals. The dead were carried out the back of the station, beyond the view of television cameras.

It was Argentina's deadliest train accident since Feb. 1, 1970, when a train smashed into another at full speed in suburban Buenos Aires, killing 200.

President Cristina Fernandez canceled her day's agenda due to the accident, which raised fresh doubts about government investment in the train system millions depend on. While largely privatized, the system depends on huge state subsidies, and fares are relatively low compared to other countries in the region.

Union leaders blamed what they called a history of failure to invest in maintaining or replacing aging trains.

The Trains of Buenos Aires company promotes its low fares on its website, saying that passengers pay just 23 cents a ride on average, compared to 80 cents in Santiago, Chile, and $1.11 in Sao Paulo.

But the TBA also complained that without higher fares, it has struggled to maintain the trains. Employee salaries and benefits have soared nearly 900 percent in the last decade, while the TBA now spends just 12 percent of its operating costs on maintenance.

The company offered its condolences in a statement that said it was cooperating with authorities investigating the cause of the accident.

``This is not an accident whose causes will be hidden from view in any way,'' Schiavi promised, noting that recorders, security cameras, computer systems and other evidence would be handed to investigators.

``We have a lot of evidence that will show the cause of this accident,'' he said.

There have been a half-dozen serious train accidents in Argentina in the last 15 months. Last September, a bus driver crossed the tracks in front of an oncoming train, killing 11 people. Two months later, a bus driver transporting children on a field trip drove in front of a train, killing eight schoolgirls.

``The series of train accidents hurts, and exposes the reality of a state incapable of controlling and acting to protect the passengers,'' opposition leader Ricardo Alfonsin tweeted.