D.C. Mayor Muriel Bowser, right, flanked by City Administrator Rashad Young, left, and Deputy Administrator Kevin Donahue, center, talks about the fatal Metro train incident in January. (Linda Davidson/The Washington Post)

A computer system used to dispatch D.C. firetrucks and ambulances has malfunctioned almost daily since it was installed in the fall, slowing response times to their worst levels in more than two years and leaving dispatchers blind to whether they are sending the closest units to fires and medical emergencies.

D.C. Mayor Muriel E. Bowser (D) told the D.C. Council on Tuesday that her administration had begun emergency work to fix the system and will soon deploy additional ambulances and take other precautions to compensate for the troubled system.

The disclosure came five days after the death of a toddler who had choked on a grape in his family’s Northwest Washington home. In that incident, D.C. paramedics just blocks from the home were not dispatched; instead, a unit located about a mile away was sent and took almost seven minutes to arrive.

The mayor’s office launched an investigation after finding that paramedics assigned to the closer ambulance were not properly logged into the system and, therefore, were invisible to dispatchers.

Kevin Donahue, Bowser’s deputy mayor for public safety, told council members that the administration has already uncovered a widespread problem that needs immediate action.

Tablet computers installed in ambulances and firetrucks beginning in late October have routinely lost their 4G network signals as the vehicles traverse the city, at times providing dispatchers with inaccurate information about unit location when deciding which are best positioned to respond to 911 calls.

In an interview Tuesday with The Washington Post, José Cuesta, the father of the 18-month-old boy who died, said he blames the malfunctioning dispatch system for the death of his son.

“I know there was a problem. . . . here were minutes in which we waited,” said Cuesta, an economist at the World Bank and a professor at Georgetown University. Cuesta said he can’t help but wonder whether his son would be alive if the closest paramedic had been sent. “I think that probably cost the life of my son,” he said.

Donahue said it was unclear how many times the dispatch system had malfunctioned, but more than 1,000 incident tickets have been generated in the past four months by IT workers at a help desk for D.C. firefighters and paramedics.

Firefighters’ calls for technical support shot up 800 percent in the month after the system was introduced. They have leveled off at more than 200 a month, or four times as many as before the new dispatch system was installed.

Although Donahue said that fixing the system was an urgent matter, he said residents should still have faith in the District’s 911 system, and he played down concerns expressed by council members that it could be affecting response times.

“Often, it will not affect the time it will take for a paramedic or a first responder to get to the scene,” Donahue said.

But information made available to the public shows widespread and significant delays in the arrival times of first responders and ambulances since the new system was introduced.

In February, the percentage of critical medical calls in which a first responder arrived within 6 1/2 minutes fell to 82 percent, from 94 percent a year earlier. And the average wait for an ambulance increased by more than 1 1/2 minutes, to almost eight minutes.

Donahue said Bowser’s new chief technology officer had identified 19 problems with the system in the past week and had corrected 11 of them. The rest could be fixed within a week, he said.

Until it’s clear that the system is working properly, Donahue has ordered all ambulances to use redundant radio communications and to call dispatchers when they hear units that may be farther from the scene being sent to an emergency.

Bowser has also ordered an additional 11 a.m.-to-11 p.m. overtime shift for ambulances, so that all 49 available units are on the road during peak hours for service calls. The city has a fleet of 98 ambulances, but only about half are in good working order and available for use. It has been standard practice to use about 36 ambulance and medical units on any one shift, Donahue said.

Several administration officials, who spoke on the condition of anonymity because the city could face legal action over response times, said the tablet system appears to malfunction when switching between 4G network bands and WiFi hotspots.

During a network switch, the vehicles can go off-line and dispatchers can be left seeing only the last known position. The problem is occurring routinely at hospitals when trucks drive under concrete pavilions or into bays to deliver patients.

The system was purchased through a $13 million contract with PCN Strategies, and the tablets were manufactured by Getac, an administration official said. Neither company could immediately be reached for comment.

Until further notice, all D.C. ambulance drivers are being instructed to report by radio when leaving hospitals, and the fire department is stationing supervisors at emergency rooms to help ambulance units get back into service more quickly.

In an interview, Donahue stressed that the public should still have confidence in the city’s 911 system.

“In nearly every case, paramedics and firefighters are getting to the scene promptly, but we don’t have a margin for error and need to make sure that happens all of the time,” he said.

Edward C. Smith, head of the D.C. firefighters union, applauded the mayor for acknowledging the problem, but he said it remains acute.

Smith said that on Friday night, the tablet in Rescue Squad 1, the truck he was assigned to for an overnight shift in Chinatown, was off-line for hours, despite repeated calls for IT help.

“I couldn’t get logged in all night, and we were calling all night,” Smith said. “For a department that has been in turmoil, we have taken one thing that was working and added it on top of all of the other problems.”

A call to the District’s Office of Unified Communications, which runs the 911 call center and oversaw the contract for the tablets, was returned by the mayor’s office. Earlier this month, officials with the OUC blamed firefighters for not using the system as they were trained to do.

On Tuesday, Bowser said the problems were not limited to firefighters and paramedics and were a result of moving too quickly to implement the system in the waning months of Mayor Vincent C. Gray’s term. “Let’s just say, it was rushed,” she said.

The mayor’s acknowledgment of a problem with the dispatch system follows a series of highly publicized delays in the fire department’s response to medical emergencies.

At least one was caused by the malfunctioning system, one of the administration officials said. When a motorcycle driver was thrown from his bike during a downtown collision this month, an ambulance that gone offline appeared more than a mile closer than it was. The ambulance was over 3 and a half miles away and the victim waited for over 20 minutes.

Donahue said that during the March 13 choking incident, the paramedic in the closest truck had logged into the new system but had not taken a second step: noting that his truck also carried paramedic equipment. Donahue said that appeared to be the reason that the system did not recognize that he was closer to the child than the paramedic who was dispatched.

Speaking Tuesday after he returned home from a midday Mass to remember his son, Cuesta said he wants to know that the city is fixing the system but has been too focused on grieving for his son to consider action against the city. “It’s something I need to work out,” he said.

Peter Hermann contributed to this report.